| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Record high °F (°C) | 76 (24) | 80 (27) | 84 (29) | 90 (32) | 95 (35) | 105 (41) | 105 (41) | 105 (41) | 101 (38) | 90 (32) | 83 (28) | 79 (26) | 105 (41) |
| Mean maximum °F (°C) | 65.0 (18.3) | 67.1 (19.5) | 74.7 (23.7) | 80.8 (27.1) | 88.3 (31.3) | 96.5 (35.8) | 99.6 (37.6) | 96.9 (36.1) | 92.9 (33.8) | 84.1 (28.9) | 73.6 (23.1) | 65.3 (18.5) | 100.6 (38.1) |
| Mean daily maximum °F (°C) | 44.6 (7.0) | 45.7 (7.6) | 55.7 (13.2) | 61.7 (16.5) | 71.2 (21.8) | 83.4 (28.6) | 89.9 (32.2) | 87.5 (30.8) | 79.6 (26.4) | 65.3 (18.5) | 52.9 (11.6) | 44.0 (6.7) | 65.1 (18.4) |
| Daily mean °F (°C) | 31.7 (−0.2) | 32.7 (0.4) | 41.6 (5.3) | 47.8 (8.8) | 57.4 (14.1) | 68.2 (20.1) | 75.1 (23.9) | 72.9 (22.7) | 64.8 (18.2) | 51.1 (10.6) | 39.4 (4.1) | 31.2 (−0.4) | 51.2 (10.6) |
| Mean daily minimum °F (°C) | 18.7 (−7.4) | 19.7 (−6.8) | 27.5 (−2.5) | 33.9 (1.1) | 43.6 (6.4) | 53.0 (11.7) | 60.2 (15.7) | 58.3 (14.6) | 50.0 (10.0) | 37.0 (2.8) | 26.0 (−3.3) | 18.4 (−7.6) | 37.2 (2.9) |
| Mean minimum °F (°C) | −3.8 (−19.9) | −1.5 (−18.6) | 9.5 (−12.5) | 19.8 (−6.8) | 30.2 (−1.0) | 41.9 (5.5) | 51.4 (10.8) | 48.8 (9.3) | 35.9 (2.2) | 19.6 (−6.9) | 5.4 (−14.8) | −3.4 (−19.7) | −11.0 (−23.9) |
| Record low °F (°C) | −29 (−34) | −25 (−32) | −11 (−24) | −2 (−19) | 19 (−7) | 30 (−1) | 42 (6) | 40 (4) | 17 (−8) | −2 (−19) | −18 (−28) | −25 (−32) | −29 (−34) |
| Averageprecipitation inches (mm) | 0.38 (9.7) | 0.41 (10) | 0.86 (22) | 1.68 (43) | 2.16 (55) | 1.94 (49) | 2.14 (54) | 1.58 (40) | 1.35 (34) | 0.99 (25) | 0.64 (16) | 0.35 (8.9) | 14.48 (368) |
| Average snowfall inches (cm) | 6.4 (16) | 7.6 (19) | 8.8 (22) | 6.2 (16) | 1.4 (3.6) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.8 (2.0) | 3.9 (9.9) | 7.3 (19) | 6.6 (17) | 49.0 (124) |
| Average extreme snow depth inches (cm) | 3.8 (9.7) | 4.7 (12) | 4.0 (10) | 2.2 (5.6) | 0.5 (1.3) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.1 (0.25) | 2.0 (5.1) | 4.1 (10) | 5.3 (13) | 9.0 (23) |
| Average precipitation days(≥ 0.01 in) | 4.4 | 5.5 | 6.2 | 9.0 | 10.4 | 8.1 | 8.3 | 7.5 | 6.0 | 5.3 | 4.6 | 4.4 | 79.7 |
| Average snowy days(≥ 0.1 in) | 5.0 | 5.3 | 4.8 | 4.1 | 0.8 | 0.0 | 0.0 | 0.0 | 0.4 | 1.8 | 4.6 | 4.6 | 31.4 |
| Averagerelative humidity (%) | 55.2 | 55.8 | 53.7 | 49.6 | 51.7 | 49.3 | 47.8 | 49.3 | 50.1 | 49.2 | 56.3 | 56.6 | 52.0 |
| Averagedew point °F (°C) | 12.7 (−10.7) | 16.2 (−8.8) | 19.9 (−6.7) | 26.2 (−3.2) | 35.8 (2.1) | 43.5 (6.4) | 48.4 (9.1) | 47.7 (8.7) | 39.6 (4.2) | 28.6 (−1.9) | 21.0 (−6.1) | 14.2 (−9.9) | 29.5 (−1.4) |
| Mean monthlysunshine hours | 215.3 | 211.1 | 255.6 | 276.2 | 290.0 | 315.3 | 325.0 | 306.4 | 272.3 | 249.2 | 194.3 | 195.9 | 3,106.6 |
| Mean dailydaylight hours | 9.7 | 10.7 | 12.0 | 13.3 | 14.4 | 15.0 | 14.7 | 13.7 | 12.4 | 11.1 | 10.0 | 9.4 | 12.2 |
| Percentagepossible sunshine | 72 | 70 | 69 | 69 | 65 | 70 | 71 | 72 | 73 | 72 | 65 | 67 | 70 |
| Averageultraviolet index | 2 | 2 | 3 | 3 | 5 | 6 | 6 | 5 | 5 | 3 | 2 | 2 | 4 |
| Source 1: NOAA (sun, relative humidity and dew point 1961−1990)[1][2][3][4][5] | |||||||||||||
| Source 2: Weather Atlas (Daylight-Average UV index)[6] | |||||||||||||