Plymouth, MN 55485 Frost Dates
Frost dates for Plymouth, MN, ZIP 55485
Around 04/29 is the usual last spring frost, about 244 days away. The first fall frost typically arrives around 10/12, about 163 frost-free days later.
The USDA Plant Hardiness Zone Map puts Plymouth in Zone 5a (-20 to -15°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 5a around Plymouth has about 6 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 04/29 isn't a guarantee
04/29 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Plymouth compares
About 163 days separate Plymouth's last and first frost, putting it 31,293 of 40,283 ZIP codes nationally. Within MN, it ranks 138 of 943.
Learn more
local microclimates explains what one yard in Plymouth can differ from the 55485 normal, and zone vs. frost date explains why Zone 5a and Plymouth's frost date answer different questions.