Frost Dates for 53039 — Juneau, Wisconsin

Half of springs at Horicon Wwtp, WI see their last 32°F night by May 1; only one in ten is past it by April 16, and one in ten still has one after May 19. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 13 20%, and after May 19 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 96% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 10 in half of years, as early as September 27 one year in ten, and holds off past October 24 one year in ten. A hard freeze of 28°F follows 11 days later, around October 21; in spring the one-in-ten date for 28°F is May 5, 14 days before the 32°F one. The freeze-free season lasts 158 days in a typical year, longer than at 56% of the 182 Wisconsin stations; it reaches 180 days one year in ten and falls short of 135 one year in ten. On average 155 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 12 days longer, to about May 13, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 22 and March 21.

July is the warmest month at Horicon Wwtp, WI, averaging 80°F by day and 60°F at night; January is the coldest at 25°F and 9°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 53% of years.

Warmth for growing adds up to 2,404 growing degree days a year (base 50°F), fewer than at 53% of the 182 Wisconsin stations. 32% of them (777) have built up by the end of June, and July adds the most, 622. Precipitation totals 35.4 inches a year, most in June (5.0") and least in February (1.3"); May to September bring 57% of it.

The nearest other station, Hustisford Wwtp, WI, 6 miles southeast of Juneau, has a last frost 3 days earlier (April 28), the same first-frost date, a season 6 days longer.

The first measurable snow (0.1 inch or more) in Juneau usually arrives around November 22, and the last of the season around March 30. Those are the middle dates across the winters of 1991–2020 at Horicon Wwtp, WI, 5.7 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 32 days after the last snow.

ZIP 53039 is 6 miles from Horicon Wwtp, WI, which stands at 881 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 53050 (Mayville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 53039 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.