Frost Dates for 53531 — Deerfield, Wisconsin

Half of springs at Lake Mills Wwtp, WI see their last 32°F night by April 29; 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 7 20%, and after May 13 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 14 in half of years, as early as September 29 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 12 days later, around October 26; 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 167 days in a typical year, longer than at 79% of the 182 Wisconsin stations; it reaches 186 days one year in ten and falls short of 146 one year in ten. On average 145 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 8, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 24 and March 18.

July is the warmest month at Lake Mills Wwtp, WI, averaging 84°F by day and 62°F at night; January is the coldest at 27°F and 11°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 44% of years.

Warmth for growing adds up to 2,830 growing degree days a year (base 50°F), more than at 93% of the 182 Wisconsin stations. 33% of them (947) have built up by the end of June, and July adds the most, 711. Precipitation totals 37.0 inches a year, most in June (5.1") and least in January (1.4"); May to September bring 59% of it.

The nearest other station, Waterloo Wwtp, WI, 11 miles northeast of Deerfield, has a last frost 1 day later (April 30), a first frost 5 days earlier (October 9), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Deerfield usually arrives around November 23, and the last of the season around March 28. Those are the middle dates across the winters of 1991–2020 at Lake Mills Wwtp, WI, 10.1 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 53531 is 10 miles from Lake Mills Wwtp, WI, which stands at 811 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 53551 (Lake Mills). The 2023 USDA Plant Hardiness Zone Map lists ZIP 53531 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.