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 May.

Other Month’s Climatologies

January
February
March
April
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.

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: The most common wind direction for this month by frequency of occurrence is due south (~13%).

Directions that are most and least common: Due northeast (11.5%) winds present a second maximum of most frequent winds. The least common wind direction is east-southeast (~2%), followed by due east (~2.25%).

Direction(s) most likely to produce the fastest winds: Due northwest winds have a slim possibility of generating winds over 21.5 knots. No other wind direction seems to have a measurable occurrence of winds exceeding this speed. This is a marked difference from the previous two months when wind speeds of this magnitude were much more common. Winds of 16.5-21.4 knots are most frequently found coming from the west-northwest, due northwest, north-northwest, and due south.

Direction(s) least likely to produce the fastest winds: Due east, east-southeast, and due southeast winds rarely exceed 16.4 knots.

Impacts of wind direction on local weather: The most common wind directions in May differ from the previous two months, with northwesterly winds becoming less frequent, while southerly and northeasterly winds become more prominent. In fact, winds from the southern semicircle are generally more common than previous months. Cold air advection from northwest winds continue to influence temperatures in the wake of cold fronts approaching from the west, however, the effect should be dramatic than in prior spring months. Winds from the northeast can be associated to backdoor cold fronts arriving from the Canadian Maritimes, bringing a moist, cool maritime polar air mass; the advance of coastal Nor’easter type storms; or a warm front approaching from the south. The difference between sea surface temperatures and temperatures over land widens during May as daily normal highs increase. This increases the chances for sea breezes during periods of overall weak synoptic winds, though generally, southerly winds would allow for advection of warmer, more moist airmasses into the area. This would often be the case when the NYC region is in the warm sector of mid-latitude lows, preceding the passage of a typical cold front attached such lows.

Maximum observed two-minute wind speed for the month: 36 (41 mph)

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth Noting: Average temperatures climb above 70ºF in May for the first time during the spring months. In 2019, new record lows were set for the 13th and 14th of May, at 42ºF and 44ºF respectively. In 2020, an all-time monthly record low of 36ºF was set on May 9th. In 2021, record lowest max temperatures were set for the 29th and 30th (52ºF, brrr), and record lows were set for the 29th-31st (48ºF, 48ºF, and 50ºF respectively)!

Date	Normal High	Normal Low	Record High	Record Low	Record Lowest Max	Record Highest Min	Normal Precip	Record Precip
1	67	49	85	38	50	62	0.10	2.18
2	67	50	90	40	47	67	0.12	0.83
3	67	50	93	40	50	70	0.11	1.45
4	67	50	92	41	49	72	0.12	0.89
5	68	51	90	42	46	65	0.12	2.27
6	68	51	93	41	47	61	0.11	1.28
7	68	51	93	40	44	60	0.12	1.11
8	69	51	89	37	49	68	0.11	2.28
9	69	52	92	36	46	76	0.12	1.21
10	69	52	91	38	53	71	0.11	1.44
11	70	52	96	42	51	68	0.11	1.77
12	70	53	88	43	50	68	0.11	1.30
13	70	53	89	42	55	67	0.11	1.74
14	71	53	84	44	54	64	0.11	2.82
15	71	54	92	43	53	65	0.11	0.89
16	71	54	90	41	53	63	0.12	2.57
17	72	54	94	38	56	68	0.12	1.03
18	72	54	97	44	54	80	0.12	1.44
19	72	55	96	43	50	68	0.12	2.00
20	72	55	97	44	52	77	0.14	1.79
21	73	55	93	45	51	71	0.13	1.60
22	73	56	94	47	57	70	0.14	0.95
23	73	56	94	45	55	69	0.14	1.72
24	74	56	91	41	54	72	0.13	1.82
25	74	57	95	44	47	74	0.14	1.64
26	74	57	94	45	55	75	0.13	1.59
27	75	57	92	41	48	73	0.13	1.84
28	75	58	92	44	58	73	0.13	1.41
29	75	58	95	48	52	71	0.14	2.41
30	76	58	96	48	52	74	0.14	2.19
31	76	59	96	50	60	78	0.14	2.23
Range	67-76	49-59	84-97	37-50	44-60	60-80	0.10-0.14	0.83-2.82