Hallowell, ME 04239 Frost Dates
Frost dates for Hallowell, ME, ZIP 04239
Around 05/11 is the usual last spring frost, about 256 days away. The first fall frost typically arrives around 09/29, about 138 frost-free days later.
Zone 5a (-20 to -15°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 Hallowell, not a forecast for this year.
What to do before the first frost
Zone 5a around Hallowell has about 5 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 05/11 isn't a guarantee
05/11 is the middle of 30 years of NOAA records, not a promise. Plant by 04/29 and you're betting against frost in roughly 9 years out of 10. 05/24 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Hallowell compares
About 138 days separate Hallowell's last and first frost, putting it 37,394 of 40,283 ZIP codes nationally. Within ME, it ranks 374 of 456.
Learn more
zone vs. frost date explains why Zone 5a and Hallowell's frost date answer different questions, and the frost range explains how to read the range around Hallowell's dates instead of trusting one.