Climate averages 1991–2020
Boston weather
by month.
See how the year changes. July has the highest average daily maximum; July has the lowest average monthly rainfall.
Long-term climate patterns, not a forecast for a particular trip.
Across the year Boston averages a daytime high of 14.5°C and a nighttime low of 5.8°C, with about 1,125 mm of rain on roughly 119 days. July is the warmest month (average high 27.5°C) and January the coolest (1.5°C). March is the wettest month with 116 mm; July is the driest with 73 mm.
The annual picture
A year in Boston
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Boston climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 1.5°C-7.2°C | -7.2°C | 94 | 10.0 | 9.59 h |
| February | 2.8°C-6.3°C | -6.3°C | 84 | 8.9 | 10.511 h |
| March | 6.7°C-2.4°C | -2.4°C | 116 | 11.1 | 11.912 h |
| April | 13.2°C3.5°C | 3.5°C | 100 | 11.0 | 13.313 h |
| May | 18.8°C9.3°C | 9.3°C | 81 | 10.6 | 14.615 h |
| June | 24.1°C14.9°C | 14.9°C | 87 | 10.1 | 15.215 h |
| July | 27.5°C18.4°C | 18.4°C | 73 | 9.6 | 14.915 h |
| August | 26.6°C17.9°C | 17.9°C | 85 | 9.1 | 13.914 h |
| September | 22.4°C14.1°C | 14.1°C | 88 | 8.1 | 12.513 h |
| October | 16.0°C8.1°C | 8.1°C | 108 | 9.8 | 11.111 h |
| November | 9.8°C2.4°C | 2.4°C | 95 | 9.6 | 9.810 h |
| December | 4.4°C-3.1°C | -3.1°C | 115 | 10.8 | 9.19 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
Nearby cities
- DorchesterUnited States · 7 kmHigh 14.4°C · Low 6.2°C · 1,125 mm rain a year
- NewtonUnited States · 13 kmHigh 14.7°C · Low 6.2°C · 1,074 mm rain a year
- QuincyUnited States · 13 kmHigh 14.2°C · Low 6.7°C · 1,125 mm rain a year
- LynnUnited States · 15 kmHigh 13.3°C · Low 6.7°C · 1,133 mm rain a year
- BrocktonUnited States · 31 kmHigh 14.5°C · Low 6.7°C · 1,104 mm rain a year
- LowellUnited States · 37 kmHigh 14.6°C · Low 5.6°C · 1,058 mm rain a year
- Lawrence (Massachusetts), United StatesUnited States · 40 kmHigh 14.5°C · Low 5.7°C · 1,058 mm rain a year
- NashuaUnited States · 56 kmHigh 14.3°C · Low 5.1°C · 1,068 mm rain a year
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC-5, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 42.40°, -71.10° (6 km from the city centre), adjusted down by 0.1°C for the difference between the city's elevation (38 m) and the cell's (26 m). Rain comes from the 0.25° cell at 42.25°, -71.00°. Dorchester and Quincy lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.