Boston, MA Weather
Boston hourly forecast: next 24 hours
Today's high of 79°F (26°C) is about 5°F (3°C) above the typical September high of 74°F (23°C).
Current conditions in detail
Boston weather tomorrow (Friday, September 18)
Tomorrow in Boston looks overcast, with a high of 76° and an overnight low of 63°. There is a 57% chance of rain - plan accordingly. Winds top out near 12 mph, and the UV index reaches 6 (moderate).
Boston 14-day forecast
About the weather in Boston
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.
Boston weather: quick facts
- 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%
Temperatures through 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.
Rain, sun and snow
Snow falls on roughly 16 days a year, mostly December through April.
Season by season
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.
Average temperatures in Boston by month
| Month | High | Low | Rain days | Precipitation | Sunshine | Humidity |
|---|---|---|---|---|---|---|
| January | 37° | 23° | 10 | 4.2 in | 6.0 h/day | 67% |
| February | 40° | 22° | 10 | 3.5 in | 6.7 h/day | 69% |
| March | 46° | 29° | 12 | 4.3 in | 7.9 h/day | 67% |
| April | 56° | 39° | 12 | 4.2 in | 8.4 h/day | 69% |
| May | 67° | 49° | 11 | 3.1 in | 10.2 h/day | 70% |
| June | 77° | 59° | 11 | 3.4 in | 11.2 h/day | 71% |
| July | 83° | 66° | 12 | 4.3 in | 11.4 h/day | 72% |
| August | 82° | 65° | 11 | 2.9 in | 10.9 h/day | 73% |
| September | 74° | 59° | 9 | 4.3 in | 8.9 h/day | 75% |
| October | 63° | 48° | 10 | 4.7 in | 7.5 h/day | 76% |
| November | 51° | 36° | 8 | 3.3 in | 6.6 h/day | 71% |
| December | 42° | 28° | 11 | 4.7 in | 5.7 h/day | 73% |