Concord, NH 03307 Frost Dates
03307, near Concord, NH: the frost window
The last spring frost here typically falls around 05/08, about 253 days from today. Fall's first freeze usually shows up around 10/03, roughly 146 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Concord in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Concord's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/08 isn't a guarantee
05/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/22 and only about 1 year in 10 sees frost after that.
Concord against the rest of the dataset
Concord's growing season runs about 146 days, ranking 36,010 of 40,283 US ZIP codes measured here, longest to shortest. Within NH, it ranks 162 of 260.
Learn more
Two guides worth reading on 03307: local microclimates, on what one yard in Concord can differ from the 03307 normal, and zone vs. frost date, on why Zone 5b and Concord's frost date answer different questions.