Photo: 4300streetcar · CC BY 4.0Somerville’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 82°, a January night drops to 20°, and about 49 inches of snow falls in a normal winter.
A year in Somerville at a glance
Each month’s typical high and low, and what it brings.
What stands out about Somerville’s climate
Compared with towns across the U.S., with Somerville’s place in Massachusetts beside it.
What a year in Somerville feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 218 frost-free days a year
In half of years the last 32° night comes by April 4 and the first by November 9. Frost and day counts come from NOAA’s station at Boston Logan International Airport, 5 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Somerville’s center in zone 6b: the coldest night of a typical winter, averaged over 1991–2020, reaches about 0°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 49 inches of snow a winter
Snow, measured at Boston Logan International Airport, is heaviest from January through February, about 14 inches a month. Precipitation (rain plus melted snow) adds up to 48 inches a year; December is the wettest month and February the driest. Rain or snow falls on about 128 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Somerville
87% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through April.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Boston Logan International Airport.
Living with Somerville’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
218 frost-free days in zone 6b. The last frost comes by Apr 4 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Nov 9.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August, September and October. 1.9 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Somerville from natural hazards, river flooding is the largest share (71%); heat waves, cold waves, winter storms and ice storms together are 8%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Somerville and its neighbors
Arlington has the coldest January nights next door (19°, 2° colder). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Somerville’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Somerville, MA | 20° | 82° | 48" | 49" |
| Indiana, PA | 19° | 83° | 46" | 46" |
| Oak Hill, WV | 24° | 82° | 48" | 56" |
| Carmel, NY | 18° | 83° | 48" | 40" |
| Newton, NJ | 18° | 83° | 47" | 39" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
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°).
A bigger shift than in 91% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Somerville compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Somerville’s place among Massachusetts’.
Somerville weather by month
Highs, lows and precipitation from NOAA’s grid at Somerville’s center; snow, wet days and snow on the ground from Boston Logan International Airport. 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" | 0.0" | 12 | 52° – 62° |
| June | 77° | 57° | 4.1" | 0.0" | 11 | 63° – 70° |
| July | 82° | 64° | 3.5" | 0.0" | 9 | 68° – 76° |
| August | 81° | 62° | 3.6" | 0.0" | 9 | 68° – 75° |
| September | 73° | 55° | 3.8" | 0.0" | 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 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 17° to 37°. August is the most reliable, staying within 7°.
Where Somerville’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Somerville’s center.
- Snow: Boston Logan International Airport.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Boston Logan International Airport, 5 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Somerville’s climate
What is the weather like in Somerville?
A typical July afternoon reaches 82°, a January night drops to 20°, and about 49 inches of snow falls in a normal winter. Colder January nights than 57% of U.S. towns; cooler July afternoons than 79% of U.S. towns.
How cold does it get in Somerville in winter?
January nights average 20°. About 92 nights a year reach 32° or below. In the coldest January of the last 30 years the month averaged 19°.
How much snow does Somerville get?
About 49 inches in a normal winter at Boston Logan International Airport, heaviest from January through February, about 14 inches a month.
How hot does it get in Somerville?
July, with a typical high of 82° and a low of 64°. About 14 days a year reach 90° (Boston Logan International Airport).
When is the first and last frost in Somerville?
In half of years the last spring frost (32°) comes by April 4 and the first fall frost by November 9, about 218 frost-free days, at Boston Logan International Airport.
What growing zone is Somerville in?
Zone 6b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 0°.
What is the best time of year to visit Somerville?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August, September and October. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Somerville getting warmer?
Yes: 1991–2020 averaged 2.0° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 91% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Somerville.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.