Brookston, MN 55779 Frost Dates
Brookston, MN: when does the frost end?
Around 05/18 is the usual last spring frost, about 263 days away. Fall's first freeze usually shows up around 10/01, roughly 135 days after the last spring frost.
Brookston sits in USDA Zone 4a (-30 to -25°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.
Stretching the season past the first frost
With roughly 5 weeks until Brookston's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/18 isn't a guarantee
05/18 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/02 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/03 and only about 1 year in 10 sees frost after that.
Brookston against the rest of the dataset
About 135 days separate Brookston's last and first frost, putting it 37,932 of 40,283 ZIP codes nationally. Within MN, it ranks 808 of 943.
Learn more
Before leaning on 55779's figures: zone vs. frost date explains why Zone 4a and Brookston's frost date answer different questions, while the frost range explains how to read the range around Brookston's dates instead of trusting one.