Plymouth, MN 55480 Frost Dates
55480, near Plymouth, MN: the frost window
Typically, the last spring freeze lands around 04/29, roughly 244 days out. Fall's first freeze usually shows up around 10/12, roughly 163 days after the last spring frost.
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.
Stretching the season past the first frost
Plymouth'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 04/29 isn't a guarantee
04/29 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Plymouth against the rest of the dataset
At roughly 163 frost-free days, Plymouth places 31,290 of 40,283 ZIP codes in this dataset. Within MN, it ranks 135 of 943.
Learn more
Two guides worth reading on 55480: local microclimates, on what one yard in Plymouth can differ from the 55480 normal, and zone vs. frost date, on why Zone 5a and Plymouth's frost date answer different questions.