Frost Dates for 56551 — Henning, Minnesota

Half of springs at Ottertail, MN see their last 32°F night by May 5; only one in ten is past it by April 24, and one in ten still has one after May 18. Planting tender crops after May 10 leaves a 30% risk of a frost on them, after May 14 20%, and after May 18 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 5 in half of years, as early as September 23 one year in ten, and holds off past October 19 one year in ten. A hard freeze of 28°F follows 10 days later, around October 15; in spring the one-in-ten date for 28°F is May 10, 8 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, longer than at 57% of the 142 Minnesota stations; it reaches 169 days one year in ten and falls short of 136 one year in ten. On average 172 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 14, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 11 and April 3.

July is the warmest month at Ottertail, MN, averaging 79°F by day and 60°F at night; January is the coldest at 17°F and -2°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 72% of years.

Warmth for growing adds up to 2,187 growing degree days a year (base 50°F), fewer than at 66% of the 142 Minnesota stations. 31% of them (683) have built up by the end of June, and July adds the most, 601.

The nearest other station, New York Mills, MN, 15 miles north of Henning, has a last frost 5 days later (May 10), a first frost 6 days earlier (September 29), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Henning usually arrives around November 4, and the last of the season around April 21. Those are the middle dates across the winters of 1991–2020 at Ottertail, MN, 8 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 14 days after the last snow.

ZIP 56551 is 8 miles from Ottertail, MN, which stands at 1,349 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 56515 (Battle Lake). The 2023 USDA Plant Hardiness Zone Map lists ZIP 56551 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°C) over 1991–2020; a zone describes winter lows, not frost dates.