Calais, ME 04491 Frost Dates
Calais, ME: when does the frost end?
Around 05/02 is the usual last spring frost, about 247 days away. Fall's first freeze usually shows up around 10/15, roughly 164 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Calais in Zone 5a (-20 to -15°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
With roughly 7 weeks until Calais's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
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 30,954 of 40,283 ZIP codes in this dataset. Within ME, it ranks 134 of 456.
Learn more
Before leaning on 04491's figures: the frost range explains how to read the range around Calais's dates instead of trusting one, while local microclimates explains what one yard in Calais can differ from the 04491 normal.