Somerville, MA climate
Somerville has chilly, snowy winters and pleasant summers. A typical July afternoon reaches 82°, a January night drops to 20°, and about 49 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Somerville feels like
Winter
Spring
Summer
Fall
Somerville weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | 30-yr range |
|---|---|---|---|---|---|---|
| January | 37° | 20° | 3.6" | 14.3" | 12 | 19° – 35° |
| February | 39° | 22° | 3.4" | 14.4" | 11 | 17° – 37° |
| March | 46° | 29° | 4.5" | 9.0" | 12 | 32° – 46° |
| April | 57° | 38° | 4.1" | 1.6" | 12 | 44° – 52° |
| May | 67° | 48° | 3.6" | 0 | 12 | 52° – 62° |
| June | 77° | 57° | 4.1" | 0 | 11 | 63° – 70° |
| July | 82° | 64° | 3.5" | 0 | 9 | 68° – 76° |
| August | 81° | 62° | 3.6" | 0 | 9 | 68° – 75° |
| September | 73° | 55° | 3.8" | 0 | 9 | 61° – 68° |
| October | 62° | 44° | 4.6" | 0.2" | 11 | 49° – 60° |
| November | 51° | 35° | 3.9" | 0.7" | 10 | 38° – 48° |
| December | 42° | 26° | 4.7" | 9.0" | 12 | 28° – 44° |
| Year | 59° | 42° | 47.5" | 49.2" | 128 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Somerville
Somerville gets 47 inches of rain and melted snow a year. December is the wettest month and February the driest. Rain or snow falls on about 128 days a year.
About 218 frost-free days a year
In half of years the last 32° night comes by April 4 and the first one by November 9. That leaves about 218 frost-free days for gardens, longer than 81% of U.S. towns.
Heating and cooling a home in Somerville
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Somerville, 87% of that work is heating and 13% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Somerville and its neighbors
Somerville borders 5 towns with climate data. January nights across them vary by 1.9°. Arlington has both the coldest January nights (19°) and the hottest July afternoons (83°). Somerville’s January low is 20° and its July high 82°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Somerville compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Somerville averaged 2.0° warmer than the 1900s. The biggest change is in December (+3.6°). The shift is larger than in 95% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Somerville’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 17° to 37°. August is the most reliable, staying within 7°.
Common questions about Somerville’s climate
What is the coldest month in Somerville?
January, with a typical high of 37° and a low of 20°.
What is the hottest month in Somerville?
July, with a typical high of 82° and a low of 64°. About 14 days a year reach 90°.
How much snow does Somerville get?
About 49 inches in a normal winter, most of it in February.
When is the first frost in Somerville?
In half of years the first 32° night comes by November 9, and the last spring frost by April 4.
What is the rainiest month in Somerville?
December, with 4.7 inches of rain and melted snow. The year totals 47 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Somerville itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Boston Logan Intl Airport, MA (5 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.