Somersworth, NH 03907 Frost Dates
When can you plant in Somersworth, NH?
Typically, the last spring freeze lands around 05/09, roughly 254 days out. The first fall frost typically arrives around 10/03, about 146 frost-free days later.
The USDA Plant Hardiness Zone Map puts Somersworth in Zone 6a (-10 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
About 5 weeks of growing season left in Somersworth before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/09 isn't a guarantee
05/09 is the middle of 30 years of NOAA records, not a promise. Plant by 04/28 and you're betting against frost in roughly 9 years out of 10. 05/22 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Somersworth compares
About 146 days separate Somersworth's last and first frost, putting it 36,037 of 40,283 ZIP codes nationally. Within NH, it ranks 166 of 260.
Learn more
zone vs. frost date covers why Zone 6a and Somersworth's frost date answer different questions. the frost range covers how to read the range around Somersworth's dates instead of trusting one.