Frost Dates for 56031 — Fairmont, Minnesota

Half of springs at Fairmont, MN see their last 32°F night by April 25; only one in ten is past it by April 12, and one in ten still has one after May 6. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 10%. The 11 days between the even-odds date and the one-in-ten date is the narrowest of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 14 in half of years, as early as September 30 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 10 days later, around October 24; in spring the one-in-ten date for 28°F is April 28, 8 days before the 32°F one. The freeze-free season lasts 171 days in a typical year, longer than at 92% of the 142 Minnesota stations; it reaches 189 days one year in ten and falls short of 152 one year in ten. On average 151 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 9 days longer, to about May 4, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 16 and March 23.

July is the warmest month at Fairmont, MN, averaging 83°F by day and 64°F at night; January is the coldest at 24°F and 7°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 28% of years.

Warmth for growing adds up to 2,891 growing degree days a year (base 50°F), more than at 94% of the 142 Minnesota stations. 34% of them (974) have built up by the end of June, and July adds the most, 725. Precipitation totals 33.5 inches a year, most in June (5.0") and least in January (0.9"); May to September bring 62% of it.

The nearest other station, Winnebago, MN, 17 miles northeast of Fairmont, has a last frost 2 days later (April 27), a first frost 4 days earlier (October 10), a season 5 days shorter.

The first measurable snow (0.1 inch or more) in Fairmont usually arrives around November 10, and the last of the season around April 1. Those are the middle dates across the winters of 1991–2020 at Fairmont, MN, 0.4 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 24 days after the last snow.

ZIP 56031 is under a mile from Fairmont, MN, which stands at 1,187 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 56031 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.