Minnesota frost dates

Across Minnesota, the average last spring frost is around May 6 and the average first fall frost around September 28 — roughly 145 frost-free days. USDA zones 3a, 3b, 4a, 4b, 5a.

Risk you accept	Last spring frost by	First fall frost by
Cautious (~10%)	May 20	September 14
Average (~50%)	May 6	September 28
Gambler (~90%)	April 22	October 12

→ Turn these into sowing dates with the Minnesota planting calendar, or look up an exact ZIP code.

Statewide average from NOAA/NCEI freeze normals. Cautious/gambler dates are about two weeks either side of the average.