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NYC (KLGA) Climatology for April

April 2, 2019Climate, NYCclimatology, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, sea breeze, wind roseLei Zhao

Other Month’s Climatologies

January
February
March
May
June
July
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.

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 northwest occuring about 13% of the time.

Directions that are most and least common: Most common wind directions following due northwest are due south (10%), west-northwest (9%), and due northeast (8.75%). Least common wind directions are east-southeast (1.25%), due east (2.5%), and due southeast (2.75%).

Direction(s) most likely to produce the fastest winds: Winds from the northwest, west-northwest, and to some extent the northeast and east-northeast tend to produce the fastest winds.

Direction(s) least likely to produce the fastest winds: Winds from the east-southeast, due east, and south-southwest are least likely to produce the fastest winds.

Impacts of wind direction on local weather: Like March northwesterly winds during April are likely tied to the passage of cold fronts and coastal storms. Cold air advection from these winds will still be quite robust during the beginning of the month especially, as record lows for this month suggest. Winds from the northeast are still tied to backdoor cold fronts arriving from the Canadian Maritimes, bringing a moist, cool maritime polar air mass, or the advance of coastal Nor’easter type storms. During April, sea surface temperatures around NYC become markedly cooler than the air temperature as average highs continue climbing in response to more direct sun angle on longer spring days. On days approaching record warmth, in an overall environment of otherwise light winds, you could even see some sea breezes start forming along the coasts.

Maximum observed two-minute wind speed for the month: 48 knots (55 mph).

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth Noting

April is the first month in the spring when record high temperatures exceed 90ºF. Record lows still routinely dip into the 20s during this month, reflecting the variability that spring can bring. The most recent record low was set in 2021, at 29ºF for 4/2. April also has the second highest single day precipitation record with 6.69″ falling on 4/15.

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	55	40	80	27	42	56	0.14	1.89
2	56	40	79	29	39	55	0.14	1.66
3	56	40	77	25	39	53	0.14	1.59
4	57	41	76	24	36	56	0.14	1.74
5	57	41	74	25	38	53	0.14	2.12
6	57	41	80	22	40	53	0.14	2.45
7	58	42	91	22	30	63	0.13	2.00
8	58	42	89	25	38	67	0.14	2.03
9	59	42	84	26	40	64	0.15	2.28
10	59	43	82	29	39	53	0.14	2.85
11	59	43	82	32	42	57	0.15	0.94
12	60	43	86	29	44	54	0.14	1.72
13	60	44	85	25	36	59	0.14	1.63
14	60	44	84	27	41	58	0.14	0.93
15	61	44	86	28	40	64	0.14	6.69
16	61	45	89	31	44	68	0.13	2.50
17	62	45	94	32	45	73	0.13	1.71
18	62	45	91	35	45	69	0.12	0.58
19	62	46	85	35	40	70	0.13	1.41
20	63	46	85	35	47	63	0.13	1.89
21	63	46	86	33	40	61	0.13	1.84
22	63	47	85	33	44	61	0.13	1.90
23	64	47	85	36	44	57	0.12	2.21
24	64	47	87	36	46	59	0.13	2.06
25	64	48	88	36	48	59	0.12	1.50
26	65	48	91	37	47	63	0.13	1.33
27	65	48	89	38	45	61	0.13	1.85
28	66	49	89	36	41	68	0.12	2.64
29	66	49	88	36	49	65	0.13	1.00
30	66	49	89	42	47	60	0.11	5.26
Range	55-66	40-49	74-94	22-42	30-49	53-73	0.11-0.15	0.58-6.69

NYC (KLGA) Climatology for March

March 3, 2019Climate, NYCclimatology, continental polar, maritime polar, new york city climate, new york city weather, new york city wx, nyc climate, nyc weather, nyc wx, 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. As such, I’ve decided to post some critical components of climatology for the closest station to me, LaGuardia Airport (KLGA). Below, I’ve posted some general climate data, and also specific data for the month of March.

Other Month’s Climatologies

January
February
April
May
June
July
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.

March wind rose for KLGA, source: National Resource Conservation Service

Frequency (percentage) of the single most common wind direction: Due northwest occuring about 14% of the time.

Directions that are most and least common: Most common wind directions following due northwest are due northeast (11.75%), west-northwest (10.25%), north-northwest (8.5%). Least common wind directions are east-southeast (1%), due southeast (2%), and due east (2.25%).

Direction(s) most likely to produce the fastest winds: The most common wind directions are also the ones most likely to produce the fastest winds.

Direction(s) least likely to produce the fastest winds: Again, the least common wind directions are also least likely to produce the fastest winds.

Impacts of wind direction on local weather: Prevalent northwesterly winds during this month generally follow in the wake of cold fronts and coastal storms. These winds can lead to substantial cold air advection (transport of cold, dry continental polar air mass from interior Canada), often because of subsidence in the wake cold fronts mixing down very fast winds to the surface. These winds will downslope and warm slightly as they approach the coast though. A secondary maximum of winds from the northeast can be attributed to backdoor cold fronts arriving from the Canadian Maritimes, bringing a moist, cool maritime polar air mass, or in conjunction with the advance of coastal Nor’easter type storms. During March, sea surface temperatures in the vicinity of NYC are above freezing, but by no means warm. If a warmer air mass is in place prior to winds shifting to the northeast, cooler, more moist conditions will result. If a colder, below freezing air mass is present, northeasterly winds can exert moderating influence on temperatures. Persistent northeasterly winds can also lead to the potential for coastal flooding given the shape of local coastline.

Maximum observed two-minute wind speed for the month in knots: 40 knots (46 mph).

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth Noting: Average temperatures in March rise above 50°F for the first month since November. However, March can certainly still produce cold days – many of the record lowest max temperatures are below freezing, with record lows still in the teens and single digits. It is a month indicative of spring when large temperature swings are possible.

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	45	31	71	8	25	53	0.12	2.23
2	46	31	67	13	25	50	0.11	2.44
3	46	31	65	10	25	49	0.12	2.26
4	46	31	69	7	25	46	0.11	1.53
5	46	32	72	9	25	48	0.12	0.72
6	47	32	64	14	24	48	0.12	2.47
7	47	32	69	14	25	49	0.13	1.90
8	47	32	74	14	28	54	0.12	1.20
9	47	33	75	14	26	49	0.12	2.18
10	48	33	78	12	27	62	0.12	1.52
11	48	33	70	15	30	49	0.12	1.40
12	48	33	69	15	28	49	0.12	1.83
13	49	34	83	19	33	53	0.12	3.15
14	49	34	75	18	34	50	0.12	1.41
15	49	34	74	14	29	48	0.13	1.61
16	50	34	77	19	32	51	0.13	1.12
17	50	35	74	15	26	54	0.13	1.39
18	50	35	75	13	19	51	0.14	2.05
19	51	35	72	10	26	53	0.13	1.38
20	51	36	82	19	31	53	0.14	1.18
21	51	36	70	18	34	53	0.14	2.00
22	52	36	76	19	33	54	0.13	3.15
23	52	37	74	19	26	56	0.14	1.44
24	52	37	74	17	30	50	0.14	1.63
25	53	37	77	18	32	50	0.13	1.55
26	53	38	72	20	34	51	0.14	1.26
27	54	38	83	23	36	54	0.14	1.20
28	54	38	83	23	36	58	0.13	2.83
29	54	39	86	25	34	59	0.14	1.90
30	55	39	79	23	34	59	0.13	2.65
31	55	39	82	24	36	59	0.14	2.10
Range	45-55	31-39	64-86	7-25	19-36	45-62	0.11-0.14	0.72-3.15

NYC Climate Update: Possible 2019 El Niño – Jan 7, 2019

January 7, 2019Climate, Cool Images, NYC, Outside of NYCnyc climate, subtropical jetLei Zhao

The latest seasonal forecast from the Climate Prediction Center suggests a 90% chance of an El Niño forming during this winter. Because El Niño (and its opposite, La Niña) occurs when there are sea surface temperature anomalies over large portions of the equatorial Pacific, it can affect sensible weather across the world. However, even if an El Niño does form, and is potentially strong, it doesn’t mean it’s the only determining factor for climate outlooks in our region.

Climate Predicition Center’s latest ENSO Outlook as of December 13, 2018. The CPC’s forecast probability that El Niño will form and persist through April 2019 exceeds 80%.

Definition: What is El Niño?

The term El Niño refers to the large-scale ocean-atmosphere climate phenomenon linked to a periodic warming in sea-surface temperatures across the central and east-central equatorial Pacific (between approximately the date line and 120^oW)… [CPC] declares the onset of an El Niño episode when the 3-month average sea-surface temperature departure exceeds 0.5^oC in the east-central equatorial Pacific [between 5^oN-5^oS and 170^oW-120^oW].
Climate prediction center

There are links between a pattern of weakening trade winds and the onset of El Niño, though there’s no conclusive understanding of the mechanics that lead to the formation of this effect. Either way, this post will focus more on possible effects of El Niño. The key lies in the geographic extent of El Niño, impacting much of the central and east-central Pacific. Since the oceans play a pivotal role in governing global atmospheric patterns, it’s no surprise that El Niño can have global weather impacts.

General Impacts of El Niño

El Niño global impacts from The Weather Network

As you can see, impacts from a classic El Niño bring warmer than normal weather to the northern part of the western US, and cooler and wetter conditions to the Gulf Coast/Deep South. Though not official yet, it does appear an El Niño was already in progress September-November, and possibly into December. This has already brought copious rains to the Southeastern US.

Green and blue hues indicate areas that received above normal precipitation.

One of the primary ways that El Niño affects global weather is by altering the intensity, orientation, and physical extent of the subtropical jet at the 200 mb level. Over the southeastern US, El Niño promotes a stronger subtropical jet streak – this can lead to the formation of stronger than usual storms over this portion of the country, bringing above normal precipitation patterns we see above.

CPC’s analysis of atmospheric anomalies, in this sequence of images, you can see the elongation of the subtropical jet (area of yellows, oranges, reds) flowing east from Asia. Similarly, a stronger subtropical jet streak is seen over parts of the US.

El Niño doesn’t have particularly strong impacts on our area, and this is borne out by the CPC’s seasonal 3-month outlook for this winter. It appears we may see slight chances for above normal precipitation here, but about equal chances of temperature anomalies.

CPC 3-month temperature outlook
CPC 3-month precipitation outlook

Notice, however, that some of the areas forecast to experience above normal temperatures do map well with a classic El Niño’s impacts (Alaska, parts of the Pacific Northwest, extreme Northern Plains), as do parts of the southern tier (Texas, Gulf Coast).

NYC Weather Update – Mar 21, 2016

March 21, 2016Climate, NYC, Rain, Weather Updateclimate, cold front, new york city climate, new york city weather, nyc climate, nyc weather, thunderstorms, weatherLei Zhao

February 2016 resolutely smashed previous records for the largest deviation above normal temperatures for any given month (which was previously set in January 2016). Thus far, March has yielded temperatures more typical of late-May, and also two instances of late season accumulating snows. This week, the weather warms up again, and there’s certainly no snow on deck.

Rest of today – clouds have largely cleared out with the passage of last night’s coastal storm that left behind some marginal accumulations across the region, the highest totals occurring quite a ways east of the city, but capped at only about 3″. There will be no trace of the snow by this afternoon as temperatures warm into the upper-40s.

Tuesday – very similar to today, with high temperatures in the upper-40s and mostly sunny skies.

Wednesday – winds turn to the southwest ahead of an advancing frontal boundary that will pass late Thursday/Friday, allowing temperatures to surge into the low-60s with increasing clouds.

Thursday – tricky temperature forecast due to the timing of approach of the aforementioned frontal boundary. If that boundary is a bit slower than current forecasts or lifts further north, we could see temperatures well into the 60s. Temperatures should be quite mild in the mid-upper 50s even outside of this scenario.

Friday – the next chance at rain and possibly a couple of thunderstorms occurs late Thursday into Friday morning with the anticipated passage of a cold front. Despite the passage of this front, temperatures will still be well above average in the upper-50s.

LZ | Weather

Weather updates & posts for NYC region

Tag Archives: nyc climate

NYC (KLGA) Climatology for April

Other Month’s Climatologies

Station Basic Information

Local Geography and Topography

Wind Patterns

Temperature and Precipitation Averages/Records

NYC (KLGA) Climatology for March

Other Month’s Climatologies

Station Basic Information

Local Geography and Topography

Wind Patterns

Temperature and Precipitation Averages/Records

NYC Climate Update: Possible 2019 El Niño – Jan 7, 2019

NYC Weather Update – Mar 21, 2016