Frost Dates for 56065 — Mapleton, Minnesota

Half of springs at Amboy, MN see their last 32°F night by April 30; only one in ten is past it by April 14, and one in ten still has one after May 12. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 7 20%, and after May 12 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 85% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 7 in half of years, as early as September 23 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 13 days later, around October 20; in spring the one-in-ten date for 28°F is May 4, 8 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, longer than at 79% of the 142 Minnesota stations; it reaches 180 days one year in ten and falls short of 140 one year in ten. On average 156 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 September 30. Severe cold of 16°F or below comes every winter, usually between November 14 and March 22.

July is the warmest month at Amboy, MN, averaging 84°F by day and 63°F at night; January is the coldest at 26°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 46% of years.

Warmth for growing adds up to 3,001 growing degree days a year (base 50°F), more than at 98% of the 142 Minnesota stations. 36% of them (1,074) have built up by the end of June, and July adds the most, 724. Precipitation totals 32.9 inches a year, most in June (5.3") and least in January (0.8"); May to September bring 64% of it.

The nearest other station, Wells, MN, 16 miles southeast of Mapleton, has the same 50% last-frost date, a first frost 1 day earlier (October 6), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Mapleton usually arrives around November 15, and the last of the season around April 7. Those are the middle dates across the winters of 1991–2020 at Amboy, MN, 12.3 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 23 days after the last snow.

ZIP 56065 is 12 miles from Amboy, MN, which stands at 1,030 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 56065 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.