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 July.

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.

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 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.

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: 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