Calais, ME 04686 Frost Dates
04686, near Calais, ME: the frost window
The last spring frost here typically falls around 05/02, about 247 days from today. Fall's first freeze usually shows up around 10/15, roughly 164 days after the last spring frost.
Zone 5b (-15 to -10°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Calais, not a forecast for this year.
Stretching the season past the first frost
Calais's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/21 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Calais against the rest of the dataset
At roughly 164 frost-free days, Calais places 30,956 of 40,283 ZIP codes in this dataset. Within ME, it ranks 136 of 456.
Learn more
Two guides worth reading on 04686: local microclimates, on what one yard in Calais can differ from the 04686 normal, and zone vs. frost date, on why Zone 5b and Calais's frost date answer different questions.