Boston, MA Climate & Monthly Averages
Boston has a humid subtropical climate. July is the hottest month, averaging 83° by day; January is the coldest at 37°.
Boston's climate is a story of contrasts
Boston spends most of the year cold. July, the warmest month, averages 83°F (28°C) by day - a figure many cities in our dataset pass in early spring - while January holds at 37°F (3°C) with 127 wet days a year across the whole calendar.
July
83° by day 66° at nightJanuary
37° by day 23° at nightThe two ends of the year
Between the average July and the average January lie 25°C, a wider spread than roughly 82% of the cities we track. July is the warm end of the year, averaging 83°F (28°C) by day and 66°F (19°C) overnight. January bottoms out at 37°F (3°C) in daylight, 23°F (-5°C) after dark. The gridded 2015-2024 daily record for this location tops out at 101°F (39°C) and bottoms at -16°F (-26°C) - decade extremes, not all-time station records.
Three of the twelve months pair mild highs with fewer than twelve wet days; the longest unbroken run is May through June.
Snow falls on roughly 16 days a year, mostly December through April.
More climate facts for Boston
- Hottest month: July - highs near 83°F (28°C)
- Coldest month: January - highs near 37°F (3°C)
- Decade extremes (2015-2024): 101°F (39°C) high · -16°F (-26°C) low
- Wettest month: December (11 rainy days) · Sunniest: July (11.4 h sun/day)
- Climate type: humid subtropical
- Annual swing: 25°C between the average warmest and coolest month · day to night: 9°C
- Snow: about 16 days a year
- Months with freezing average lows: 4
- Average humidity: 71%
Four distinct parts of the year in Boston
Spring (March through May)
Spring in Boston stays on the cool side of mild, with daytime highs averaging 56°F (13°C) and nights around 39°F (4°C); rain falls on around 35 of the 90 days, plus about 4 snowy days.
Summer (June through August)
Through summer, Boston is mild and warm: 81°F (27°C) by day, 64°F (18°C) after dark, and rain falls on around 34 of the 90 days. Daylight is generous - around 11.2 hours of sun a day.
Fall (September through November)
Through fall, Boston is mild: 63°F (17°C) by day, 48°F (9°C) after dark, and expect showers on roughly 27 days across the season.
Winter (December through February)
Winter runs cold here - highs near 40°F (4°C), nights near 24°F (-4°C), and rain falls on around 31 of the 90 days, plus about 11 snowy days.
Boston temperature extremes in the 2015–2024 dataset
Derived from ERA5 reanalysis data, 2015–2024. Official station records may differ. Need another precipitation unit? Use the rainfall converter.
Choosing a season in Boston
Best time to visit Boston
The best time to visit Boston is generally August to October and May to June, when these are the warmest and brightest weeks of the year. Daytime temperatures in that window sit near 73°F (23°C), with rain on about 10 days a month. For the same question asked the other way round, see where else is warm in August.
What to pack
Pack for Boston with light clothing for the warm months, a heavy insulated coat, hat and gloves for winter and a compact umbrella or rain shell. Note the gap between afternoon and night: July pairs 83°F (28°C) with 66°F (19°C).
Monthly highs, lows and seasonal change
| Month | High | Low | Rain days | Precipitation | Sunshine | Daylight | Wet-day chance | Humidity |
|---|---|---|---|---|---|---|---|---|
| January | 37° | 23° | 10 | 4.2 in | 6.0 h/day | 9.4 h | 34% | 67% |
| February | 40° | 22° | 10 | 3.5 in | 6.7 h/day | 10.5 h | 37% | 69% |
| March | 46° | 29° | 12 | 4.3 in | 7.9 h/day | 11.8 h | 39% | 67% |
| April | 56° | 39° | 12 | 4.2 in | 8.4 h/day | 13.3 h | 39% | 69% |
| May | 67° | 49° | 11 | 3.1 in | 10.2 h/day | 14.6 h | 35% | 70% |
| June | 77° | 59° | 11 | 3.4 in | 11.2 h/day | 15.3 h | 37% | 71% |
| July | 83° | 66° | 12 | 4.3 in | 11.4 h/day | 15.0 h | 39% | 72% |
| August | 82° | 65° | 11 | 2.9 in | 10.9 h/day | 13.9 h | 34% | 73% |
| September | 74° | 59° | 9 | 4.3 in | 8.9 h/day | 12.4 h | 30% | 75% |
| October | 63° | 48° | 10 | 4.7 in | 7.5 h/day | 11.0 h | 31% | 76% |
| November | 51° | 36° | 8 | 3.3 in | 6.6 h/day | 9.7 h | 28% | 71% |
| December | 42° | 28° | 11 | 4.7 in | 5.7 h/day | 9.1 h | 34% | 73% |
Boston from the coldest month to the hottest
Each card shows the average high and low. The bar places that month between Boston's coldest night and warmest afternoon.
January
- Rain
- 10 days
- Sunshine
- 6.0 h
- Daylight
- 9.4 h
- Snow
- 4 days
February
- Rain
- 10 days
- Sunshine
- 6.7 h
- Daylight
- 10.5 h
- Snow
- 5 days
March
- Rain
- 12 days
- Sunshine
- 7.9 h
- Daylight
- 11.8 h
- Snow
- 3 days
April
- Rain
- 12 days
- Sunshine
- 8.4 h
- Daylight
- 13.3 h
- Snow
- 1 day
May
- Rain
- 11 days
- Sunshine
- 10.2 h
- Daylight
- 14.6 h
June
- Rain
- 11 days
- Sunshine
- 11.2 h
- Daylight
- 15.3 h
July
- Rain
- 12 days
- Sunshine
- 11.4 h
- Daylight
- 15.0 h
August
- Rain
- 11 days
- Sunshine
- 10.9 h
- Daylight
- 13.9 h
September
- Rain
- 9 days
- Sunshine
- 8.9 h
- Daylight
- 12.4 h
October
- Rain
- 10 days
- Sunshine
- 7.5 h
- Daylight
- 11.0 h
November
- Rain
- 8 days
- Sunshine
- 6.6 h
- Daylight
- 9.7 h
December
- Rain
- 11 days
- Sunshine
- 5.7 h
- Daylight
- 9.1 h
- Snow
- 2 days
Looking for warmer alternatives? Browse warm places by month, or compare Boston's coolest part of the year: January, February, December.
Where Boston sits among other climates
- 27% of the year's precipitation falls in its wettest three months - more evenly spread than almost every other city we track.
These comparisons use the same ten-year window for every city in the dataset.