Frost Dates for 54966 — Plainfield, Wisconsin

Half of springs at Hancock Exp Farm, WI see their last 32°F night by May 10; only one in ten is past it by April 25, and one in ten still has one after May 24. Planting tender crops after May 16 leaves a 30% risk of a frost on them, after May 20 20%, and after May 24 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 3 in half of years, as early as September 20 one year in ten, and holds off past October 16 one year in ten. A hard freeze of 28°F follows 11 days later, around October 14; in spring the one-in-ten date for 28°F is May 15, 9 days before the 32°F one. The freeze-free season lasts 146 days in a typical year, shorter than at 73% of the 182 Wisconsin stations; it reaches 165 days one year in ten and falls short of 126 one year in ten. On average 160 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 20, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 14 and March 30.

July is the warmest month at Hancock Exp Farm, WI, averaging 82°F by day and 59°F at night; January is the coldest at 25°F and 7°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 75% of years.

Warmth for growing adds up to 2,407 growing degree days a year (base 50°F), fewer than at 52% of the 182 Wisconsin stations. 33% of them (795) have built up by the end of June, and July adds the most, 625. Precipitation totals 34.4 inches a year, most in June (5.0") and least in February (1.0"); May to September bring 60% of it.

The nearest other station, Wisconsin Rapids, WI, 19 miles northwest of Plainfield, has a last frost 1 day earlier (May 9), a first frost 3 days earlier (September 30), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Plainfield usually arrives around November 15, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Hancock Exp Farm, WI, 7.2 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 28 days after the last snow.

ZIP 54966 is 7 miles from Hancock Exp Farm, WI, which stands at 1,092 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 54982 (Wautoma). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54966 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.