Portland, ME 04109 Frost Dates
Frost dates for Portland, ME, ZIP 04109
The last spring frost here typically falls around 04/26, about 241 days from today. The first fall frost typically arrives around 10/15, about 170 frost-free days later.
The USDA Plant Hardiness Zone Map puts Portland in Zone 6a (-10 to -5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 6a around Portland has about 7 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.
The actual range around Portland's last frost
04/26 is the middle of 30 years of NOAA records, not a promise. Plant by 04/16 and you're betting against frost in roughly 9 years out of 10. 05/07 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Portland compares
About 170 days separate Portland's last and first frost, putting it 28,887 of 40,283 ZIP codes nationally. Within ME, it ranks 121 of 456.
Learn more
zone vs. frost date explains why Zone 6a and Portland's frost date answer different questions, and the frost range explains how to read the range around Portland's dates instead of trusting one.