Somersworth, NH 03878 Frost Dates
Somersworth, NH: when does the frost end?
Typically, the last spring freeze lands around 04/30, roughly 245 days out. Fall's first freeze usually shows up around 10/09, roughly 161 days after the last spring frost.
Zone 6a (-10 to -5°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Somersworth, not a forecast for this year.
Stretching the season past the first frost
With roughly 6 weeks until Somersworth's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
04/30 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/13 and only about 1 year in 10 sees frost after that.
Somersworth against the rest of the dataset
Somersworth's growing season runs about 161 days, ranking 31,997 of 40,283 US ZIP codes measured here, longest to shortest. Within NH, it ranks 66 of 260.
Learn more
Before leaning on 03878's figures: the frost range explains how to read the range around Somersworth's dates instead of trusting one, while local microclimates explains what one yard in Somersworth can differ from the 03878 normal.