Frost Dates for 53929 — Elroy, Wisconsin

Half of springs at Hillsboro, WI see their last 32°F night by May 5; only one in ten is past it by April 22, and one in ten still has one after May 18. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 14 20%, and after May 18 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 84% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 4 in half of years, as early as September 23 one year in ten, and holds off past October 18 one year in ten. A hard freeze of 28°F follows 13 days later, around October 17; in spring the one-in-ten date for 28°F is May 7, 11 days before the 32°F one. The freeze-free season lasts 153 days in a typical year, shorter than at 57% of the 182 Wisconsin stations; it reaches 173 days one year in ten and falls short of 135 one year in ten. On average 163 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 11 days longer, to about May 16, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 18 and March 24.

July is the warmest month at Hillsboro, WI, averaging 83°F by day and 60°F at night; January is the coldest at 27°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 67% of years.

Warmth for growing adds up to 2,574 growing degree days a year (base 50°F), more than at 67% of the 182 Wisconsin stations. 33% of them (853) have built up by the end of June, and July adds the most, 662. Precipitation totals 37.3 inches a year, most in June (5.1") and least in February (1.2"); May to September bring 60% of it.

The nearest other station, Hillsboro 2SW, WI, 9 miles southwest of Elroy, has a last frost 7 days later (May 12), a first frost 5 days earlier (September 29), a season 15 days shorter.

The first measurable snow (0.1 inch or more) in Elroy usually arrives around November 26, and the last of the season around April 10. Those are the middle dates across the winters of 1991–2020 at Hillsboro, 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 25 days after the last snow.

ZIP 53929 is 7 miles from Hillsboro, WI, which stands at 940 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 53929 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.