| Climate data for Islip, New York (Long Island MacArthur Airport), 1991–2020 normals,[a] extremes 1963–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 69 (21) |
71 (22) |
82 (28) |
94 (34) |
98 (37) |
96 (36) |
104 (40) |
100 (38) |
94 (34) |
89 (32) |
80 (27) |
77 (25) |
104 (40) |
| Mean maximum °F (°C) | 58.2 (14.6) |
57.1 (13.9) |
66.7 (19.3) |
77.0 (25.0) |
85.8 (29.9) |
90.4 (32.4) |
94.0 (34.4) |
91.2 (32.9) |
86.0 (30.0) |
78.6 (25.9) |
68.8 (20.4) |
60.9 (16.1) |
95.6 (35.3) |
| Mean daily maximum °F (°C) | 39.2 (4.0) |
41.0 (5.0) |
47.7 (8.7) |
58.3 (14.6) |
68.3 (20.2) |
77.2 (25.1) |
82.8 (28.2) |
81.4 (27.4) |
74.8 (23.8) |
64.1 (17.8) |
53.6 (12.0) |
44.4 (6.9) |
61.1 (16.2) |
| Daily mean °F (°C) | 31.9 (−0.1) |
33.3 (0.7) |
39.9 (4.4) |
49.7 (9.8) |
59.5 (15.3) |
69.0 (20.6) |
75.0 (23.9) |
73.7 (23.2) |
66.9 (19.4) |
55.7 (13.2) |
45.6 (7.6) |
37.1 (2.8) |
53.1 (11.7) |
| Mean daily minimum °F (°C) | 24.6 (−4.1) |
25.5 (−3.6) |
32.0 (0.0) |
41.2 (5.1) |
50.8 (10.4) |
60.9 (16.1) |
67.3 (19.6) |
66.0 (18.9) |
58.9 (14.9) |
47.3 (8.5) |
37.6 (3.1) |
29.8 (−1.2) |
45.2 (7.3) |
| Mean minimum °F (°C) | 7.4 (−13.7) |
9.8 (−12.3) |
17.0 (−8.3) |
28.8 (−1.8) |
37.9 (3.3) |
48.4 (9.1) |
57.7 (14.3) |
55.7 (13.2) |
45.4 (7.4) |
33.0 (0.6) |
22.9 (−5.1) |
15.8 (−9.0) |
5.4 (−14.8) |
| Record low °F (°C) | −8 (−22) |
−14 (−26) |
0 (−18) |
16 (−9) |
32 (0) |
42 (6) |
49 (9) |
45 (7) |
38 (3) |
23 (−5) |
11 (−12) |
−1 (−18) |
−14 (−26) |
| Average precipitation inches (mm) | 3.66 (93) |
3.29 (84) |
4.51 (115) |
4.06 (103) |
3.28 (83) |
4.00 (102) |
3.26 (83) |
4.24 (108) |
3.60 (91) |
3.97 (101) |
3.41 (87) |
4.71 (120) |
45.99 (1,168) |
| Average snowfall inches (cm) | 10.3 (26) |
9.4 (24) |
6.5 (17) |
0.6 (1.5) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.5 (1.3) |
4.5 (11) |
31.8 (81) |
| Average precipitation days (≥ 0.01 in) | 11.1 | 9.9 | 10.8 | 11.3 | 11.6 | 10.1 | 9.1 | 8.9 | 8.6 | 9.2 | 9.6 | 11.8 | 122.0 |
| Average snowy days (≥ 0.1 in) | 3.8 | 3.7 | 2.7 | 0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.3 | 2.6 | 13.4 |
| Source: NOAA[1][2] | |||||||||||||
- ^ Mean monthly maxima and minima (i.e. the expected highest and lowest temperature readings at any point during the year or given month) calculated based on data at said location from 1991 to 2020.
- ^ "NowData – NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved August 9, 2021.
- ^ "Station: Islip LI MacArthur AP, NY". U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991–2020). National Oceanic and Atmospheric Administration. Retrieved August 9, 2021.