| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Record high °F (°C) | 74 (23) |
73 (23) |
89 (32) |
94 (34) |
97 (36) |
100 (38) |
104 (40) |
102 (39) |
102 (39) |
90 (32) |
83 (28) |
76 (24) |
104 (40) |
| Mean maximum °F (°C) | 58.3 (14.6) |
57.9 (14.4) |
67.0 (19.4) |
79.9 (26.6) |
88.1 (31.2) |
92.2 (33.4) |
95.0 (35.0) |
93.7 (34.3) |
88.9 (31.6) |
79.6 (26.4) |
70.2 (21.2) |
61.2 (16.2) |
96.4 (35.8) |
| Mean daily maximum °F (°C) | 36.8 (2.7) |
39.0 (3.9) |
45.5 (7.5) |
56.4 (13.6) |
66.5 (19.2) |
76.2 (24.6) |
82.1 (27.8) |
80.4 (26.9) |
73.1 (22.8) |
62.1 (16.7) |
51.6 (10.9) |
42.2 (5.7) |
59.3 (15.2) |
| Daily mean °F (°C) | 29.9 (−1.2) |
31.8 (−0.1) |
38.3 (3.5) |
48.6 (9.2) |
58.4 (14.7) |
68.0 (20.0) |
74.1 (23.4) |
72.7 (22.6) |
65.6 (18.7) |
54.8 (12.7) |
44.7 (7.1) |
35.7 (2.1) |
51.9 (11.1) |
| Mean daily minimum °F (°C) | 23.1 (−4.9) |
24.6 (−4.1) |
31.1 (−0.5) |
40.8 (4.9) |
50.3 (10.2) |
59.7 (15.4) |
66.0 (18.9) |
65.1 (18.4) |
58.2 (14.6) |
47.5 (8.6) |
37.9 (3.3) |
29.2 (−1.6) |
44.5 (6.9) |
| Mean minimum °F (°C) | 4.8 (−15.1) |
8.3 (−13.2) |
15.6 (−9.1) |
31.0 (−0.6) |
41.2 (5.1) |
49.7 (9.8) |
58.6 (14.8) |
57.7 (14.3) |
46.7 (8.2) |
35.1 (1.7) |
24.4 (−4.2) |
13.1 (−10.5) |
2.6 (−16.3) |
| Record low °F (°C) | −13 (−25) |
−18 (−28) |
−8 (−22) |
11 (−12) |
31 (−1) |
41 (5) |
50 (10) |
46 (8) |
34 (1) |
25 (−4) |
−2 (−19) |
−17 (−27) |
−18 (−28) |
| Average precipitation inches (mm) | 3.39 (86) |
3.21 (82) |
4.17 (106) |
3.63 (92) |
3.25 (83) |
3.89 (99) |
3.27 (83) |
3.23 (82) |
3.56 (90) |
4.03 (102) |
3.66 (93) |
4.30 (109) |
43.59 (1,107) |
| Average snowfall inches (cm) | 14.3 (36) |
14.4 (37) |
9.0 (23) |
1.6 (4.1) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.0 (0.0) |
0.2 (0.51) |
0.7 (1.8) |
9.0 (23) |
49.2 (125) |
| Average precipitation days (≥ 0.01 in) | 11.8 | 10.6 | 11.6 | 11.6 | 11.8 | 10.9 | 9.4 | 9.0 | 9.0 | 10.5 | 10.3 | 11.9 | 128.4 |
| Average snowy days (≥ 0.1 in) | 6.6 | 6.2 | 4.4 | 0.8 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | 0.6 | 4.2 | 23.0 |
| Average relative humidity (%) | 62.3 | 62.0 | 63.1 | 63.0 | 66.7 | 68.5 | 68.4 | 70.8 | 71.8 | 68.5 | 67.5 | 65.4 | 66.5 |
| Average dew point °F (°C) | 16.5 (−8.6) |
17.6 (−8.0) |
25.2 (−3.8) |
33.6 (0.9) |
45.0 (7.2) |
55.2 (12.9) |
61.0 (16.1) |
60.4 (15.8) |
53.8 (12.1) |
42.8 (6.0) |
33.4 (0.8) |
22.1 (−5.5) |
38.9 (3.8) |
| Mean monthly sunshine hours | 163.4 | 168.4 | 213.7 | 227.2 | 267.3 | 286.5 | 300.9 | 277.3 | 237.1 | 206.3 | 143.2 | 142.3 | 2,633.6 |
| Percent possible sunshine | 56 | 57 | 58 | 57 | 59 | 63 | 65 | 64 | 63 | 60 | 49 | 50 | 59 |
| Average ultraviolet index | 1 | 2 | 4 | 5 | 7 | 8 | 8 | 8 | 6 | 4 | 2 | 1 | 5 |
| Source 1: NOAA (relative humidity, dew point and sun 1961−1990)[2][3][4] | |||||||||||||
| Source 2: Weather Atlas (UV)[5] | |||||||||||||
| Climate data for Boston, Massachusetts | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average sea temperature °F (°C) | 41.3 (5.2) |
38.1 (3.4) |
38.4 (3.5) |
43.1 (6.2) |
49.2 (9.5) |
58.4 (14.7) |
65.7 (18.7) |
67.9 (20.0) |
64.8 (18.2) |
59.4 (15.3) |
52.3 (11.3) |
46.6 (8.2) |
52.1 (11.2) |
| Source: Weather Atlas[5] | |||||||||||||