Frost Dates for 53588 — Spring Green, Wisconsin

Half of springs at Lone Rock Tri Co Airport, WI see their last 32°F night by April 30; only one in ten is past it by April 15, and one in ten still has one after May 14. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 9 20%, and after May 14 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 9 in half of years, as early as September 25 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 9 days later, around October 18; in spring the one-in-ten date for 28°F is May 5, 9 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, longer than at 62% of the 182 Wisconsin stations; it reaches 181 days one year in ten and falls short of 142 one year in ten. On average 151 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 9, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 18 and March 18.

July is the warmest month at Lone Rock Tri Co Airport, WI, averaging 83°F by day and 61°F at night; January is the coldest at 28°F and 10°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 2,745 growing degree days a year (base 50°F), more than at 86% of the 182 Wisconsin stations. 35% of them (953) have built up by the end of June, and July adds the most, 682. Precipitation totals 34.2 inches a year, most in June (5.3") and least in January (0.9"); May to September bring 62% of it.

The nearest other station, Mazomanie Wwtp, WI, 13 miles east of Spring Green, has a last frost 7 days later (May 7), a first frost 8 days earlier (October 1), a season 13 days shorter.

The first measurable snow (0.1 inch or more) in Spring Green usually arrives around December 2, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Mazomanie Wwtp, WI, 12.8 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 40 days after the last snow.

ZIP 53588 is 6 miles from Lone Rock Tri Co Airport, WI, which stands at 717 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 53588 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.