Calais, ME 04497 Frost Dates
04497, near Calais, ME: the frost window
The last spring frost here typically falls around 05/25, about 270 days from today. Fall's first freeze usually shows up around 09/24, roughly 119 days after the last spring frost.
Calais sits in USDA Zone 4b (-25 to -20°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
Calais's growing season runs out in roughly 4 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/25 isn't a guarantee
05/25 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/10 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/08 and only about 1 year in 10 sees frost after that.
Calais against the rest of the dataset
Calais's growing season runs about 119 days, ranking 39,143 of 40,283 US ZIP codes measured here, longest to shortest. Within ME, it ranks 443 of 456.
Learn more
Two guides worth reading on 04497: local microclimates, on what one yard in Calais can differ from the 04497 normal, and zone vs. frost date, on why Zone 4b and Calais's frost date answer different questions.