Zimmerman, MN 55398 Frost Dates
Zimmerman, MN: when does the frost end?
The last spring frost here typically falls around 05/04, about 249 days from today. Fall's first freeze usually shows up around 10/05, roughly 154 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Zimmerman in Zone 4b (-25 to -20°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 5 weeks until Zimmerman's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/04 isn't a guarantee
05/04 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/18 and only about 1 year in 10 sees frost after that.
Zimmerman against the rest of the dataset
At roughly 154 frost-free days, Zimmerman places 34,261 of 40,283 ZIP codes in this dataset. Within MN, it ranks 386 of 943.
Learn more
Before leaning on 55398's figures: local microclimates explains what one yard in Zimmerman can differ from the 55398 normal, while zone vs. frost date explains why Zone 4b and Zimmerman's frost date answer different questions.