Somerville, NJ climate
Somerville has chilly winters and warm summers, with plenty of rain. A typical July afternoon reaches 87°, a January night drops to 22°, and about 21 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 | 40° | 22° | 3.5" | 6.8" | 10 | 23° – 38° |
| February | 43° | 24° | 2.8" | 6.7" | 8 | 22° – 40° |
| March | 51° | 30° | 4.1" | 3.6" | 10 | 35° – 50° |
| April | 63° | 40° | 3.8" | 0.2" | 11 | 48° – 56° |
| May | 73° | 49° | 4.2" | 0 | 12 | 57° – 66° |
| June | 82° | 59° | 4.5" | 0 | 11 | 67° – 74° |
| July | 87° | 64° | 5.1" | 0 | 10 | 71° – 79° |
| August | 85° | 62° | 4.6" | 0 | 10 | 69° – 77° |
| September | 78° | 56° | 4.3" | 0 | 9 | 64° – 71° |
| October | 66° | 43° | 4.4" | 0.1" | 10 | 50° – 61° |
| November | 55° | 34° | 3.3" | 0.1" | 9 | 40° – 49° |
| December | 45° | 27° | 4.3" | 3.5" | 10 | 29° – 47° |
| Year | 64° | 43° | 48.7" | 21.0" | 121 |
“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 49 inches of rain and melted snow a year. July is the wettest month and February the driest. Rain or snow falls on about 121 days a year.
About 176 frost-free days a year
In half of years the last 32° night comes by April 26 and the first one by October 18. That leaves about 176 frost-free days for gardens, shorter than 53% 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, 86% of that work is heating and 14% 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 3 towns with climate data. January nights across them vary by 0.6°. Bridgewater has the coldest January nights (22°) and Hillsborough the hottest July afternoons (87°). Somerville’s January low is 22° and its July high 87°.
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 2.3° warmer than the 1900s. The biggest change is in December (+4.0°). The shift is larger than in 99% 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. December swings the most: between 1991 and 2020 its average temperature ranged from 29° to 47°. June 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 40° and a low of 22°.
What is the hottest month in Somerville?
July, with a typical high of 87° and a low of 64°. About 23 days a year reach 90°.
How much snow does Somerville get?
About 21 inches in a normal winter, most of it in January.
When is the first frost in Somerville?
In half of years the first 32° night comes by October 18, and the last spring frost by April 26.
What is the rainiest month in Somerville?
July, with 5.1 inches of rain and melted snow. The year totals 49 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 Bound Brook 2w, NJ (2 mi, snow) and Somerville Somerset Airport, NJ (5 mi, frost, heat and degree days). Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.