Humboldt, MN 56731 Frost Dates
When can you plant in Humboldt, MN?
Typically, the last spring freeze lands around 05/16, roughly 261 days out. The first fall frost typically arrives around 09/29, about 137 frost-free days later.
The USDA Plant Hardiness Zone Map puts Humboldt in Zone 3b (-35 to -30°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 5 weeks of growing season left in Humboldt before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/16 isn't a guarantee
05/16 is the middle of 30 years of NOAA records, not a promise. Plant by 05/02 and you're betting against frost in roughly 9 years out of 10. 05/31 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Humboldt compares
About 137 days separate Humboldt's last and first frost, putting it 37,606 of 40,283 ZIP codes nationally. Within MN, it ranks 792 of 943.
Learn more
zone vs. frost date covers why Zone 3b and Humboldt's frost date answer different questions. the frost range covers how to read the range around Humboldt's dates instead of trusting one.