Waterville, ME 04903 Frost Dates
04903, near Waterville, ME: the frost window
Typically, the last spring freeze lands around 05/02, roughly 247 days out. Fall's first freeze usually shows up around 10/10, roughly 159 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 Waterville, not a forecast for this year.
Stretching the season past the first frost
Waterville'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.
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 04/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Waterville against the rest of the dataset
About 159 days separate Waterville's last and first frost, putting it 32,599 of 40,283 ZIP codes nationally. Within ME, it ranks 161 of 456.
Learn more
Two guides worth reading on 04903: local microclimates, on what one yard in Waterville can differ from the 04903 normal, and zone vs. frost date, on why Zone 5b and Waterville's frost date answer different questions.