Dover, NH 03820 Frost Dates
03820, near Dover, NH: the frost window
Around 05/03 is the usual last spring frost, about 248 days away. Fall's first freeze usually shows up around 10/10, roughly 158 days after the last spring frost.
Dover sits in USDA Zone 6a (-10 to -5°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
Dover'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.
The actual range around Dover's last frost
05/03 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/16 and only about 1 year in 10 sees frost after that.
Dover against the rest of the dataset
Dover's growing season runs about 158 days, ranking 32,895 of 40,283 US ZIP codes measured here, longest to shortest. Within NH, it ranks 74 of 260.
Learn more
Two guides worth reading on 03820: zone vs. frost date, on why Zone 6a and Dover's frost date answer different questions, and the frost range, on how to read the range around Dover's dates instead of trusting one.