Frost Dates for 53578 — Prairie Du Sac, Wisconsin

Half of springs at Sauk City Wwtp, WI see their last 32°F night by May 4; only one in ten is past it by April 20, and one in ten still has one after May 18. Planting tender crops after May 10 leaves a 30% risk of a frost on them, after May 13 20%, and after May 18 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 6 in half of years, as early as September 23 one year in ten, and holds off past October 21 one year in ten. A hard freeze of 28°F follows 13 days later, around October 19; 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 155 days in a typical year, shorter than at 51% of the 182 Wisconsin stations; it reaches 174 days one year in ten and falls short of 136 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 11 days longer, to about May 15, and return around September 27. Severe cold of 16°F or below comes every winter, usually between November 18 and March 22.

July is the warmest month at Sauk City Wwtp, WI, averaging 82°F by day and 59°F at night; January is the coldest at 27°F and 8°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 61% of years.

Warmth for growing adds up to 2,523 growing degree days a year (base 50°F), more than at 61% of the 182 Wisconsin stations. 33% of them (840) have built up by the end of June, and July adds the most, 642. Precipitation totals 36.3 inches a year, most in June (5.3") and least in January (1.3"); May to September bring 60% of it.

The nearest other station, Baraboo, WI, 10 miles north of Prairie Du Sac, has a last frost 1 day later (May 5), a first frost 1 day earlier (October 5), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Prairie Du Sac usually arrives around November 22, and the last of the season around March 27. Those are the middle dates across the winters of 1991–2020 at Baraboo, WI, 9.7 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 38 days after the last snow.

ZIP 53578 is 4 miles from Sauk City Wwtp, WI, which stands at 750 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 53578 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.