Rochester, NH 03225 Frost Dates
03225, near Rochester, NH: the frost window
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.
Rochester sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Rochester's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/30 isn't a guarantee
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.
Rochester against the rest of the dataset
Rochester's growing season runs about 161 days, ranking 31,952 of 40,283 US ZIP codes measured here, longest to shortest. Within NH, it ranks 54 of 260.
Learn more
Two guides worth reading on 03225: local microclimates, on what one yard in Rochester can differ from the 03225 normal, and zone vs. frost date, on why Zone 5b and Rochester's frost date answer different questions.