Frost Dates for 56159 — Mountain Lake, Minnesota

Half of springs at Windom, MN see their last 32°F night by April 30; only one in ten is past it by April 15, and one in ten still has one after May 13. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 8 20%, and after May 13 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 10 in half of years, as early as September 25 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 11 days later, around October 21; in spring the one-in-ten date for 28°F is May 3, 10 days before the 32°F one. The freeze-free season lasts 162 days in a typical year, longer than at 81% of the 142 Minnesota stations; it reaches 182 days one year in ten and falls short of 142 one year in ten. On average 162 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 8 days longer, to about May 8, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 15 and March 25.

July is the warmest month at Windom, MN, averaging 84°F by day and 63°F at night; January is the coldest at 25°F and 8°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 47% of years.

Warmth for growing adds up to 2,952 growing degree days a year (base 50°F), more than at 96% of the 142 Minnesota stations. 34% of them (1,013) have built up by the end of June, and July adds the most, 739. Precipitation totals 31.8 inches a year, most in June (4.7") and least in February (0.8"); May to September bring 63% of it.

The nearest other station, St James Wwtp, MN, 16 miles east of Mountain Lake and 314 feet lower, has the same 50% last-frost date, a first frost 3 days earlier (October 7), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Mountain Lake usually arrives around November 6, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Windom, MN, 10.3 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 25 days after the last snow.

ZIP 56159 is 10 miles from Windom, MN, which stands at 1,384 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 56101 (Windom). The 2023 USDA Plant Hardiness Zone Map lists ZIP 56159 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.