Plymouth, MN 55459 Frost Dates
Plymouth, MN: when does the frost end?
Around 04/29 is the usual last spring frost, about 244 days away. 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
With roughly 6 weeks until Plymouth's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
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 31,284 of 40,283 ZIP codes in this dataset. Within MN, it ranks 129 of 943.
Learn more
Before leaning on 55459's figures: local microclimates explains what one yard in Plymouth can differ from the 55459 normal, while zone vs. frost date explains why Zone 5a and Plymouth's frost date answer different questions.