Frost Dates for 54025 — Somerset, Wisconsin

Half of springs at Stillwater 1 SE, MN see their last 32°F night by April 22; only one in ten is past it by April 7, and one in ten still has one after May 6. Planting tender crops after April 28 leaves a 30% risk of a frost on them, after May 1 20%, and after May 6 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 58% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 19 in half of years, as early as October 3 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 11 days later, around October 30; in spring the one-in-ten date for 28°F is April 27, 9 days before the 32°F one. The freeze-free season lasts 178 days in a typical year, longer than at 92% of the 182 Wisconsin stations; it reaches 200 days one year in ten and falls short of 157 one year in ten. On average 147 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 10 days longer, to about May 2, and return around October 8. Severe cold of 16°F or below comes every winter, usually between November 20 and March 20.

July is the warmest month at Stillwater 1 SE, MN, averaging 85°F by day and 64°F at night; January is the coldest at 27°F and 9°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 20% of years.

Warmth for growing adds up to 3,188 growing degree days a year (base 50°F), more than at 99% of the 182 Wisconsin stations. 34% of them (1,079) have built up by the end of June, and July adds the most, 767. Precipitation totals 35.2 inches a year, most in June (5.4") and least in February (0.9"); May to September bring 64% of it.

The nearest other station, Stillwater 2SW, MN, 11 miles southwest of Somerset and 188 feet higher, has a last frost 8 days later (April 30), a first frost 8 days earlier (October 11), a season 15 days shorter.

The first measurable snow (0.1 inch or more) in Somerset usually arrives around November 15, and the last of the season around April 3. Those are the middle dates across the winters of 1991–2020 at Stillwater 1 SE, MN, 8.9 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 19 days after the last snow.

ZIP 54025 is 9 miles from Stillwater 1 SE, MN, which stands at 710 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 54016 (Hudson). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54025 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.