Tag Archives: warm front

NYC (KLGA) Climatology for October

October 2, 2019Climate, NYCclimatology, cold front, high pressure, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, warm front, wind roseLei Zhao

During my time taking classes as part of Penn State University’s Undergraduate Certificate in Weather Forecasting, we were taught that understanding the climatology of the location you are interested in is an important prerequisite for making accurate forecasts. This post continues on this theme, adding a climatology for October.

Other Month’s Climatologies

January
February
March
April
May
June
July
August
September
November
December

Station Basic Information

City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)

Local Geography and Topography

Station Elevation: 10 feet above sea level.

Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.

KLGA’s location within the broader NYC area, as seen in a Google Maps terrain view

Important Topographical Features: New York City is located in the extreme southeastern corner of New York State, bordering suburban New Jersey and Connecticut. These suburban regions combined with those in Long Island comprise the Greater New York City Metropolitan Area, which is the most populous urban agglomeration in the United States and one of the populous urbanized areas in the world with an estimated population of 18 million. New York City itself sprawls across the coastal plain around the Hudson River estuary. The terminal moraine formed by glaciers of the last Ice Age result in a ridge of higher terrain that cuts a swath from southwest to northeast across the boroughs from northern Staten Island, northern Brooklyn, southwestern through central and northeastern Queens. Otherwise, the city itself is low lying. This ridge varies in height between 200-400 feet, rising sharply from south to north, but tapering more gently north. North and west of the city (about 30-50 miles away), lie significant elevations of the Catskills (north), Poconos (west), Taconics that are part of the broader Appalachian Mountain Range. The elevations of the lower foothills can range from 1000-1500 feet. Some of the elevations in the Poconos and Catskills, west and north of KLGA respectively, peak between 2000-3000 feet. The open expanse of the Atlantic Ocean lies south of KLGA and New York City. Long Island Sound also lies east-northeast. The vast urbanized area of the NYC metropolitan region has significant effects on local microclimates via differential heating (urban heat island effect). KLGA is in a low-lying area sensitive to UHI effects and marine influences.

Per the Local Climatological Data report from the National Weather Service:

On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.
National Weather Service – NYC Office

Wind Patterns

Below is a wind rose – you can read more about how to interpret this chart here.

Frequency (percentage) of the single most common wind direction: Due southwest (9%). Note: due northeast is basically co-equal most common wind direction, perhaps only off by a fraction of a percentage point.

Directions that are most and least common: Other most common wind directions include due northeast (9%), due northwest (8.75%), and west-northwest (8.25%). Least common wind directions are east-southeast (1.8%), due southeast (2.75%), and due east (3%).

Direction(s) most likely to produce the fastest winds: Winds of 16.5-21.4 knots are most frequently found coming from due northwest. West-northwest, north-northwest, due northeast, east-northeast, and due south directions can also see less frequent winds over 21.4 knots.

Direction(s) least likely to produce the fastest winds: As is the case with several other months, the least common wind directions of due east, east-southeast, and due southeast also rarely seen winds in excess of 16.4 knots.

Impacts of wind direction on local weather: October’s wind profile is a continuation on the trend established in September where wind frequencies begin to be distributed more evenly across the compass and less focused in the south. Winds from the northwest quadrant continue to increase in frequency, along with the frequency of the fastest winds coming from these directions. Northeasterly winds still figure prominently, though slightly less so than in September. Curiously, while southerly winds generally decreased in frequency, due southwest winds tick up slightly compared to September.

In general, northwesterly winds bring cooler, drier Canadian air into the region following cold fronts. Northwesterly winds will tend to warm slightly because of compressional warming as they downslope coming off the higher terrain of the Catskills, and Poconos outside of the city. This can sometimes lead to warmer temperatures than would normally be expected for this wind direction.

Northeasterly winds, on the other hand, are often related to backdoor cold fronts sweeping from the Canadian Maritimes, the onshore flow ahead of an advancing warm front, or a passing coastal storm to the south. Southwesterly winds are still capable of bringing in oppressive heat, as seen in the temperature section below.

Maximum observed two-minute wind speed for the month: 56 knots (64 mph) – this is the fastest recorded two-minute wind speed for any calendar month.

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth noting: Even though average high temperatures in October fall into the 60s, it’s still possible to see summer-like warmth – you can see this from the record high of 95°F, set anew in 2019, and that record highs can reach into the mid-80s until late in the month. Overnight lows start to fall into the 50s and end up in the 40s by the end of the month!

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	71	56	87	39	54	73	0.13	2.24
2	70	56	95	42	56	72	0.12	1.15
3	70	56	85	40	49	69	0.12	1.07
4	70	55	86	38	53	73	0.12	1.05
5	69	55	93	38	49	69	0.13	1.58
6	69	54	92	40	54	70	0.12	1.69
7	68	54	85	40	52	72	0.12	3.44
8	68	54	89	40	46	71	0.13	3.51
9	68	53	85	40	51	71	0.13	2.00
10	67	53	89	36	47	71	0.13	2.26
11	67	53	86	36	49	71	0.13	2.59
12	67	52	86	41	52	68	0.12	4.39
13	66	52	86	39	51	70	0.12	1.63
14	66	52	82	40	51	70	0.13	1.66
15	66	51	83	39	48	68	0.13	2.55
16	65	51	82	39	49	63	0.12	1.71
17	65	51	83	38	49	66	0.12	0.95
18	64	50	82	35	47	68	0.12	1.33
19	64	50	86	32	42	68	0.12	3.62
20	64	50	79	32	44	65	0.12	2.36
21	63	49	82	33	46	64	0.12	1.81
22	63	49	83	33	48	65	0.13	2.15
23	63	49	86	32	41	67	0.12	2.47
24	62	48	80	30	50	67	0.12	1.43
25	62	48	78	37	47	61	0.12	1.52
26	62	48	76	34	41	65	0.12	3.30
27	61	48	79	33	43	66	0.11	1.76
28	61	47	80	33	45	63	0.12	2.84
29	61	47	77	33	42	63	0.11	2.78
30	60	47	81	35	45	65	0.11	1.18
31	60	46	81	33	44	62	0.12	3.30
Range	60-71	46-56	76-93	30-42	41-56	61-73	0.11-0.13	0.95-4.39

NYC (KLGA) Climatology for September

September 3, 2019Climate, NYCclimatology, cold front, high pressure, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, sea breeze, warm front, wind roseLei Zhao

Other Month’s Climatologies

January
February
March
April
May
June
July
August
October
November
December

Station Basic Information

City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)

Local Geography and Topography

Station Elevation: 10 feet above sea level.

Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.

Per the Local Climatological Data report from the National Weather Service:

On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.
National Weather Service – NYC Office

Wind Patterns

Below is a wind rose – you can read more about how to interpret this chart here.

Frequency (percentage) of the single most common wind direction: Due northeast (9.5%).

Directions that are most and least common: Most common wind directions include due south (9%), due southwest (8.5%), and northwest (8%). Least common wind directions are east-southeast (1.5%), due southeast (2.5%), and due east (3.5%).

Direction(s) most likely to produce the fastest winds: Winds of 16.5-21.4 knots are most frequently found coming from due northeast, and due northeast. North-northwest, east-northeast, and due south directions can also see less frequent winds over 21.4 knots.

Impacts of wind direction on local weather: September’s wind profile sees a shift away from the general pattern of the summer months preceding it (June, July, August) during which southerly winds are predominant, and during which due south is the single most common wind direction. April is the last calendar month when due south isn’t the single most common wind direction, so it takes quite a bit of time in order for winds to shift off this summer pattern.

The most common wind directions in September are almost evenly split between northeasterly and northwesterly and southerly and southwesterly winds in percentage terms of frequency. Northwesterly winds are notably more frequent, and faster northeasterly and northwesterly winds start to appear in September as opposed to the summer months. Northwesterly winds in general will bring cooler, drier Canadian air into the region following cold fronts. Northeasterly winds, on the other hand, are related to backdoor cold fronts sweeping from the Canadian Maritimes, the onshore flow ahead of an advancing warm front, or a passing coastal storm.

The continued downward trend in southerly winds is likely a reflection of the diminishing influence of sea breezes as average land temperatures cool while average sea surface temperatures are still close to their peak (though also cooling). The narrowing gap between these two will tend to reduce the potential for sea breeze circulations to set up. However, these sea breezes can still exert an influence on local temperature and can still provide boundaries for convection. Southwesterly winds are also similarly capable of bringing in oppressive heat, as seen in the temperature section below.

Maximum observed two-minute wind speed for the month: 44 knots (51 mph)

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth noting: September can still offer up oppressive heat, especially in the first half of the month. The monthly all-time record high of 102°F is also the second highest record temperature recorded for the year at KLGA (August has the hottest record high: 104°F). September’s monthly precipitation record of 4.63″ in one day is also has the 3rd highest single-day precipitation record after April and August. While it can get quite hot in September, it’s also possible for temperatures to get cold too, with the record low for the month in the low-40s! Average high temperatures dip back below 80°F and average lows drop below 60°F again in September after the summer months, marking a definite fall feel.

‘Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	81	67	96	55	67	78	0.11	1.20
2	81	66	102	56	65	81	0.12	2.88
3	80	66	95	54	68	77	0.12	2.33
4	80	66	93	54	66	80	0.12	3.12
5	80	66	93	54	67	79	0.12	1.00
6	80	65	96	53	62	79	0.12	3.21
7	79	65	90	53	66	74	0.12	2.37
8	79	65	95	54	65	76	0.12	3.85
9	79	64	93	53	65	77	0.11	0.56
10	78	64	95	50	67	76	0.12	1.47
11	78	64	96	51	64	78	0.12	2.93
12	78	63	94	52	68	75	0.12	3.63
13	77	63	93	50	61	75	0.13	2.93
14	77	63	92	48	63	74	0.13	2.93
15	77	62	91	49	59	76	0.13	0.82
16	76	62	95	48	62	73	0.12	4.63
17	76	62	95	48	61	79	0.12	1.65
18	76	61	89	48	64	72	0.13	1.99
19	75	61	92	49	61	72	0.13	1.62
20	75	60	90	46	61	74	0.13	1.72
21	75	60	89	43	59	73	0.13	3.02
22	74	60	93	47	56	73	0.12	1.00
23	74	59	93	42	57	77	0.12	2.14
24	73	59	91	44	52	73	0.12	1.34
25	73	59	90	42	57	72	0.13	2.84
26	73	58	90	44	57	72	0.12	3.19
27	72	58	90	43	56	73	0.13	2.72
28	72	57	84	42	56	72	0.14	3.27
29	71	57	86	43	58	72	0.14	1.85
30	71	57	88	43	56	71	0.14	1.80
Range	71-81	57-67	84-102	42-56	52-68	71-81	0.11-0.14	0.56-4.63

NYC Labor Day Weekend Weather & Hurricane Dorian Update – Aug 30, 2019

August 30, 2019Cool Images, NYC, Rain, Tropical/Hurricanes, Weather Update, Weekend2019 atlantic hurricane season, cold front, dorian, high pressure, new york city weekend weather, new york city weekend wx, nyc weekend weather, nyc weekend wx, rain, tropical cyclone, tropical weather, warm frontLei Zhao

Labor Day weekend is shaping up to be a good one overall in terms of sensible weather. A dry cold front passage today sets the stage for high pressure to take control over the remainder of the weekend. The only wrinkle is a warm front forecast to pass Monday that could bring some rain. Looking ahead into next week, a warm up should precede another cold front mid-week. The big weather story this weekend will be much further south of us, as Hurricane Dorian takes aim at Florida as a dangerous Category 4 storm.

Rest of today – sunny with high temperatures in the mid-upper 80s. Overnight lows in the upper-60s.

Saturday – high pressure starts to build from the west, which will result in a cooler weather with northerly winds. High temperatures topping out in the low-80s with lots of sun and overnight lows in the mid-60s.

Sunday – high pressure will progress east, giving us another pleasant day with lots of sun and comfortable temperatures in the low-80s. Overnight lows warm up in the upper-60s with a warm front approaching from the southwest.

Monday (Labor Day) – chance for rain during the day as a warm front, then a weakening cold front approach. High temperatures in the low-80s with mostly cloudy skies. Overnight lows around 70ºF.

Hurricane Dorian Heading Towards Florida

Over the course of the last few days, Hurricane Dorian made a pass over the Northern Lesser Antilles, hitting the Virgin Islands, and Martinique, but sparing Puerto Rico. This was a blessing for an island still recovering from the devastation of Hurricane Maria. However, because Dorian avoided the disruptive influence of high terrain in Puerto Rico, it entered the open waters of the Western Atlantic north of the island ready for continued intensification. Unfortunately, various forecast models have been consistently depicting Dorian making landfall somewhere in Florida early next week as a dangerous Category 4 hurricane packing max sustained winds of 140 mph.

Latest GOES visible satellite imagery of Hurricane Dorian

Overnight going into today, Dorian’s been steadily strengthening and is now showing a markedly more symmetrical structure than before, along with an eye developing in visible satellite imagery. This suggests that the southerly shear and dry air that was afflicting the storm yesterday has abated somewhat. At this point, there is nothing really stopping Dorian from continuing to strengthen to a major hurricane.

National Hurricane Center official forecast for Dorian as of 11AM Friday

Forecasters continue to have high confidence that Dorian will make a turn towards a more westerly direction as high pressure builds over Bermuda and keeps building to the west. This will block Dorian from taking a northerly route away from Florida. Worryingly, forecast models have trended towards a slower and more southerly track overnight, then a turn north after landfall. On this current track, a large part of Florida would be affected by the storm for a considerable amount of time, increasing the risk of damaging storm surge and inland flooding from prolonged heavy rain.

NYC Weather Update – Aug 19, 2019

August 19, 2019NYC, Rain, Severe Weather, Storms, Thunderstorms, Weather Updatenew york city weather, new york city wx, nyc weather, nyc wx, rain, thunderstorms, warm frontLei Zhao

We begin this week with some typical “dog days” of summer heat. Shower and thunderstorm chances stick around for the first half of the week with the heat and humidity providing necessary instability. A more organized threat for possibly severe thunderstorms emerges Wednesday into Thursday with a pronounced cold front forecast to move through. Behind this frontal boundary, a refreshingly cool and dry air mass is expected to take hold for the weekend.

Rest of today – hot, humid, with high temperatures in the low-90s. Heat index values in the upper-90s. Partly cloudy with a chance for scattered showers and thunderstorms later this afternoon around 5-6PM as a prefrontal trough nears. Some storms could produce heavy rain and gusty winds. Overnight lows in the mid-70s.

Tuesday – still hot but a touch drier, as a cold front pushes south overnight into Tuesday. High temperatures around 90°F. Could maybe see a scattered thunderstorm still pop up but chances are lower relative to today with less humidity and instability to work with. Overnight lows in the mid-70s.

Wednesday – the cold front passing through Tuesday lifts back north as a warm front on Wednesday. Temperatures remain warm in the upper-80s. Chance for strong to severe thunderstorms possible late in the day as a cold front pushes through. If this front pushes through faster than forecast, in the late afternoon or early evening, there’s better chances for strong storms. Otherwise, showers and thunderstorms could continue overnight with lows in the mid-70s.

Thursday – should be the last day of this spell of summer heat with high temperatures in the upper-80s possible before the cold front above clears the area. Showers and thunderstorms may linger until the front clears. Overnight lows noticeably cooler in the upper-60s behind the cold front as a cooler Canadian air mass moves through.

NYC Weather Update – Aug 11, 2019

August 12, 2019NYC, Rain, Thunderstorms, Weather Update, Weekendmcs, mesoscale convective system, new york city weather, new york city wx, nyc weather, nyc wx, thunderstorms, warm frontLei Zhao

Unsettled weather takes hold during the mid-week period as a couple prefrontal disturbances affect the area. The focus for heavier rain will be later Wednesday as a cold front approaches. Behind this cold front, conditions should improve and result in a pleasant, dry weekend.

Rest of today – mostly cloudy with a chance of isolated showers and thunderstorms later in the day as a shortwave trough lingers around the area. Temperatures in the mid-80s. Overnight lows in the low-70s.

Weather Prediction Center surface forecast for 8PM Tuesday

Storm Prediction Center severe weather outlook for Tuesday

Tuesday – shaping up to be an eventful day in regards to weather. Temperatures should rise into the low-80s with overnight lows in the low-70s. During the day, a mesoscale convective system (organized large cluster of thunderstorms) will be approaching the area from the Ohio Valley. Forecast is uncertain in terms of where the frontal boundaries in the vicinity of this MCS eventually set up. Current thinking is that we end up south of a warm front earlier in the day that will serve as the initial focus for shower and thunderstorm activity. This activity should continue and increase in intensity as the frontal boundary starts shifting south and encounters warm, moist and unstable air. There is potential for all severe hazards including hail, damaging winds, and an isolated tornado.

Wednesday – mostly cloudy with shower chances diminishing later in the day . High temperatures in the low-80s and lows in the upper-60s.

Thursday – still a possibility for lingering showers but overall a better day with mostly cloudy skies and high temperatures in the low-80s with overnight lows in the upper-60s.

NYC (KLGA) Climatology for August

August 7, 2019Climate, NYCclimatology, cold front, high pressure, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, sea breeze, warm front, wind roseLei Zhao

Other Month’s Climatologies

January
February
March
April
May
June
July
September
October
November
December

Station Basic Information

City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)

Local Geography and Topography

Station Elevation: 10 feet above sea level.

Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.

Per the Local Climatological Data from the National Weather Service:

On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.
National Weather Service – NYC Office

Wind Patterns

Below is a wind rose – you can read more about how to interpret this chart here.

Frequency (percentage) of the single most common wind direction: Due south (12.25%).

Directions that are most and least common: Most common wind directions include due southwest (10%), due northeast (9.75%), and south-southwest (8.75%). Least common wind directions are east-southeast (1%), due southeast (2.5%), and due east (2%).

Direction(s) most likely to produce the fastest winds: Winds of 16.5-21.4 knots are most frequently found coming from due northeast, and due south. It appears that due northeast also has some probability of exceeding 21.4 knots.

Impacts of wind direction on local weather: August winds continue to exhibit a distinctive summer pattern, and share many of the characteristics of the wind profiles for June and July. Southerly and southwesterly winds are a touch less common in August versus July, while northwesterly winds increase in frequency slightly. Like in July, heat waves can accompany the clockwise return flow from the southwest when subtropical Bermuda highs set up southeast of the area. A slight down tick in the frequency of southerly winds may point to a decline in sea breezes, with sea surface temperatures continuing to warm and narrowing the gap with average air temperatures. Increases in northwesterly winds could be an indication of a stronger influence from Canadian high pressure.

Maximum observed two-minute wind speed for the month: 45 (52 mph)

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	85	70	100	62	69	83	0.15	2.03
2	85	70	102	59	73	86	0.15	1.31
3	85	70	100	59	70	82	0.16	2.80
4	85	70	99	62	75	80	0.15	2.78
5	85	70	100	57	69	81	0.15	2.08
6	85	70	95	57	69	81	0.15	2.34
7	85	70	99	61	65	81	0.13	1.31
8	85	70	98	59	72	81	0.14	2.54
9	85	70	104	61	71	82	0.14	2.97
10	85	70	99	57	62	81	0.14	1.91
11	85	70	99	57	68	79	0.12	2.03
12	84	70	98	56	64	82	0.13	6.40
13	84	70	100	56	67	84	0.13	4.12
14	84	69	98	59	72	81	0.14	6.60
15	84	69	97	59	67	82	0.13	0.98
16	84	69	96	58	67	79	0.14	2.48
17	84	69	94	58	70	79	0.13	3.54
18	84	69	95	59	69	81	0.13	1.18
19	84	69	94	59	71	77	0.13	2.74
20	83	69	98	58	70	77	0.14	1.31
21	83	69	97	57	62	78	0.13	1.24
22	83	68	93	55	69	78	0.13	2.34
23	83	68	92	56	70	75	0.14	1.96
24	83	68	93	55	65	77	0.13	1.40
25	83	68	96	53	67	80	0.13	2.09
26	82	68	103	53	61	80	0.12	2.58
27	82	68	99	55	70	78	0.12	4.73
28	82	67	99	54	61	81	0.11	3.62
29	82	67	100	51	66	84	0.11	2.57
30	81	67	99	54	70	81	0.11	1.89
31	81	67	100	52	68	79	0.11	1.60
Range	81-85	67-70	92-104	51-62	61-75	75-86	0.11-0.16	0.98-6.60

NYC (KLGA) Climatology for July

July 1, 2019Climate, NYCclimatology, cold front, high pressure, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, sea breeze, warm front, warm sector, wind roseLei Zhao

Other Month’s Climatologies

January
February
March
April
May
June
August
September
October
November
December

Station Basic Information

City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)

Local Geography and Topography

Station Elevation: 10 feet above sea level.

Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.

Per the Local Climatological Data report from the National Weather Service:

On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.
National Weather Service – NYC Office

Wind Patterns

Below is a wind rose – you can read more about how to interpret this chart here.

Frequency (percentage) of the single most common wind direction: Due south (13.5%).

Directions that are most and least common: Most common wind directions include due southwest (9.5%), due northeast (9.25%), and due northwest (8.5%). Least common wind directions are east-southeast (1%), due east (2%), and due southeast (2.5%).

Direction(s) most likely to produce the fastest winds: Winds of 16.5-21.4 knots are most frequently found coming from due northwest, and due south.

Impacts of wind direction on local weather: July winds are remarkably similar to June. Southerly and southwesterly winds are a bit more common in July than in June, and northwesterly winds a little less so. This pattern of winds continues to suggest the influence of mid-latitude lows tracking inland north of the area, bringing more southerly warm sector flow. As with June, persistent, subtropical high pressures continue to be a factor at times in July over the western North Atlantic. The clockwise flow around these high pressure centers would result in more southerly and southwesterly winds, which can lead to the onset and maintenance of heat waves. Southerly winds (along with easterly and some northeasterly winds) would bring cooler, and more stable marine air, sometimes in the form of sea breezes. Sea breezes can become commonplace during this month whenever there’s light synoptic winds. At this point in the year, the average max temperatures well exceed the threshold of 5-7°F warmer than sea surface temperatures (which are slowly climbing through the mid-60s) required for sea breezes.

Maximum observed two-minute wind speed for the month: 46 (53 mph)

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth Noting

July is the month when average temperatures peak at 86ºF. However, sweltering heat is possible well beyond this point, and record highs in this month are frequently in the upper-90s. Meanwhile, record highest low temperatures can easily be in the upper-70s and low-80s – making for very uncomfortable nights. July is also on average the wettest month of the year, which makes sense given the possibility for thunderstorms and a connection to tropical moisture.

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	84	68	97	56	68	79	0.12	1.12
2	84	68	101	58	69	78	0.13	1.59
3	85	68	107	57	67	81	0.12	1.77
4	85	69	100	57	62	82	0.12	2.13
5	85	69	100	56	65	86	0.13	1.75
6	85	69	103	56	62	85	0.13	2.15
7	85	69	101	59	71	81	0.13	2.14
8	85	69	99	60	66	78	0.13	1.24
9	85	69	98	57	65	82	0.14	1.81
10	85	69	99	60	71	80	0.15	2.46
11	85	69	98	62	73	80	0.14	1.68
12	85	70	98	58	68	81	0.15	1.84
13	86	70	99	58	69	84	0.16	2.01
14	86	70	99	59	73	79	0.16	1.02
15	86	70	103	62	67	83	0.16	3.53
16	86	70	97	58	70	80	0.15	1.19
17	86	70	98	60	71	79	0.15	2.74
18	86	70	101	62	68	83	0.15	2.67
19	86	70	100	62	71	86	0.15	1.02
20	86	70	101	61	70	83	0.14	2.61
21	86	70	100	62	70	83	0.15	2.06
22	86	70	104	62	70	85	0.15	3.02
23	86	70	100	59	69	82	0.14	3.51
24	86	70	98	59	68	84	0.15	3.07
25	86	70	97	59	70	82	0.15	1.60
26	86	70	98	62	71	80	0.15	2.89
27	86	70	100	59	71	81	0.15	2.77
28	86	70	98	60	72	83	0.16	1.97
29	86	70	97	62	75	82	0.17	3.45
30	85	70	99	61	74	81	0.15	3.46
31	85	70	97	62	69	78	0.17	1.23
Range	84-86	68-70	97-107	56-62	62-75	78-86	0.12-0.17	1.02-3.53

NYC Weather Update – Jul 1, 2019

July 1, 2019NYC, Rain, Thunderstorms, Weather Updatecold front, high pressure, new york city july 4th weather, new york city weather, new york city wx, nyc july 4th weather, nyc weather, rain, thunderstorms, warm frontLei Zhao

Weather this week will mostly be governed by the presence of high pressure, with the exception of a cold front sweeping through Tuesday night into Wednesday that could bring some showers and thunderstorms. Temperatures will remain warm in the upper-80s and low-90s during this time. July 4th festivities look to be safe from any rain at this time.

Rest of today – sunny skies with high temperatures in the mid-80s. Overnight lows in the low-70s.

Tuesday – mostly sunny with high temperatures in the upper-80s, close to 90°F. Chance of showers and thunderstorms later in the day as a cold front approaches from the north. Overnight lows in the low-70s.

Wednesday – high pressure starts building again with mostly sunny skies expected. High temperatures in the upper-80s with overnight lows in the low-70s.

Climate Prediction Center forecast for temperature trends between Jul 6-10, showing possibility for above average warmth to continue into the weekend.

Thursday (Independence Day) – another day of slightly above average warmth with high temperatures forecast in the upper-80s. Increasing clouds due to the approach of a weakening warm front from the southwest. Overnight lows in the low-70s, rain should hold off for fireworks viewing.

NYC Weather Update – Jun 25, 2019

June 25, 2019NYC, Rain, Thunderstorms, Weather Updatehigh pressure, new york city weather, new york city wx, nyc weather, rain, thunderstorms, warm frontLei Zhao

Earlier showers and thunderstorms today presage the passage of a warm front over the area. Behind this, high pressure begins to build tomorrow and persists through the end of the week. Temperatures during this stretch are likely to consistently reach into the upper-80s and low-90s in the city. As if on cue, the first full week of summer this year may also see a possible heat wave.

Rest of today – clouds gradually diminishing towards the evening. A few scattered showers still possible with a cold front forecast to move through later. High temperatures in the low-80s with cloud cover in place. Overnight lows will be mild in the low-70s.

Weather Prediction Center surface forecast for 8AM Wednesday

Wednesday – relatively warm start to the day allows temperatures to climb into the low-90s in the city with the urban heat island effect. Mostly sunny skies with high pressure now in control. Overnight lows in the low-70s.

Thursday – high temperatures again into the low-90s with lots of sun. Luckily, the position of this particular high pressure doesn’t translate to the influx of a humid airmass, so the overall feel of these temperatures won’t be as muggy. Overnight lows in the low-70s.

GFS 850 mb temperature anomalies for 2PM Thursday. Warmer than normal 850 mb temperatures can be a good indicator of hot surface temperatures.

Friday – yet another day of 90°F+ temperatures possible, which would mean an official heatwave. Still mostly sunny with high pressure remaining in control over sensible weather. Overnight lows continuing to be mild, in the mid-70s. Great beach weather!

NYC Weather Update – Jun 11, 2019

June 11, 2019NYC, Rain, Thunderstorms, Weather Updatecold front, high pressure, low pressure, new york city weather, new york city wx, nyc weather, rain, subsidence, thunderstorms, warm frontLei Zhao

After a rainy start to the week, high pressure takes over during the mid-week period. Another storm system moves in Thursday. Behind this next bout of rain, a dry and mostly sunny weekend should await us.

Rest of today – skies clearing as a cold front pushing. Winds picking up with some subsidence (sinking air, since air mass behind the cold front is cooler and drier). High temperatures reaching into the upper-70s with this subsidence and some downsloping from the northwest. Overnight lows in the mid-60s.

Wednesday – high pressure remains firmly rooted over the area. High temperatures in the mid-70s with mostly sunny skies. Overnight lows in the low-60s.

Thursday – a developing low closer to the coast and another one further inland over the Great Lakes will bring showers and thunderstorms to the area. First, like Monday, a warm front will lift through earlier in the day, then a cold front is expected to follow later on. High temperatures in the low-70s due to rain and cloud cover. Overnight lows in the upper-50s.

NAM model for 1000-500 mb thickness and surface reflectivity at 8AM Thursday, showing a distinct area of rain associated to a low emerging off the coast of the Delmarva Peninsula

Friday – with a cool start, temperatures top out in the mid-70s. Mostly sunny in the wake of the cold front Thursday. Overnight lows in the low-60s.

LZ | Weather

Weather updates & posts for NYC region

Tag Archives: warm front

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