Frost Dates for 56542 — Fosston, Minnesota

Half of springs at Fosston 1 E, MN see their last 32°F night by May 15; only one in ten is past it by May 2, and one in ten still has one after May 30. Planting tender crops after May 22 leaves a 30% risk of a frost on them, after May 25 20%, and after May 30 10%. The 15 days between the even-odds date and the one-in-ten date is wider than at 64% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 26 in half of years, as early as September 10 one year in ten, and holds off past October 8 one year in ten. A hard freeze of 28°F follows 9 days later, around October 5; in spring the one-in-ten date for 28°F is May 20, 10 days before the 32°F one. The freeze-free season lasts 132 days in a typical year, shorter than at 91% of the 142 Minnesota stations; it reaches 152 days one year in ten and falls short of 109 one year in ten. On average 195 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 12 days longer, to about May 27, and return around September 14. Severe cold of 16°F or below comes every winter, usually between November 5 and April 8.

July is the warmest month at Fosston 1 E, MN, averaging 78°F by day and 55°F at night; January is the coldest at 16°F and -5°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 1,871 growing degree days a year (base 50°F), fewer than at 86% of the 142 Minnesota stations. 32% of them (607) have built up by the end of June, and July adds the most, 521.

The nearest other station, Mahnomen, MN, 21 miles southwest of Fosston, has a last frost 8 days earlier (May 7), a first frost 2 days later (September 28), a season 11 days longer.

The first measurable snow (0.1 inch or more) in Fosston usually arrives around November 2, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Red Lake Falls, MN, 33.1 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 32 days after the last snow.

ZIP 56542 is under a mile from Fosston 1 E, MN, which stands at 1,300 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 56621 (Bagley). The 2023 USDA Plant Hardiness Zone Map lists ZIP 56542 in zone 3b, the band where the coldest night of the year averaged -35 to -30°F (-37.2 to -34.4°C) over 1991–2020; a zone describes winter lows, not frost dates.