Belfast, ME 04420 Frost Dates
04420, near Belfast, ME: the frost window
Typically, the last spring freeze lands around 05/07, roughly 252 days out. Fall's first freeze usually shows up around 10/05, roughly 151 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Belfast 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
Belfast'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.
How much risk comes with planting early here
05/07 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/28 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/21 and only about 1 year in 10 sees frost after that.
Belfast against the rest of the dataset
At roughly 151 frost-free days, Belfast places 34,981 of 40,283 ZIP codes in this dataset. Within ME, it ranks 253 of 456.
Learn more
Two guides worth reading on 04420: local microclimates, on what one yard in Belfast can differ from the 04420 normal, and zone vs. frost date, on why Zone 5b and Belfast's frost date answer different questions.