Plymouth, MN 55575 Frost Dates
Frost dates for Plymouth, MN, ZIP 55575
The last spring frost here typically falls around 04/29, about 244 days from today. The first fall frost typically arrives around 10/12, about 163 frost-free days later.
Plymouth sits in USDA Zone 4b (-25 to -20°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 4b 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
Plymouth's growing season runs about 163 days, ranking 31,300 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 145 of 943.
Learn more
local microclimates explains what one yard in Plymouth can differ from the 55575 normal, and zone vs. frost date explains why Zone 4b and Plymouth's frost date answer different questions.