Somerville, MA 02143 Frost Dates
Frost dates for Somerville, MA, ZIP 02143
Typically, the last spring freeze lands around 04/04, roughly 219 days out. The first fall frost typically arrives around 11/09, about 218 frost-free days later.
The USDA Plant Hardiness Zone Map puts Somerville in Zone 7a (0 to 5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 7a around Somerville has about 10 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
04/04 is the middle of 30 years of NOAA records, not a promise. Plant by 03/25 and you're betting against frost in roughly 9 years out of 10. 04/17 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Somerville compares
Somerville's growing season runs about 218 days, ranking 13,179 of 40,283 US ZIP codes measured here, longest to shortest. Within MA, it ranks 15 of 712.
Learn more
local microclimates explains what one yard in Somerville can differ from the 02143 normal, and zone vs. frost date explains why Zone 7a and Somerville's frost date answer different questions.