Frost Dates for 54817 — Birchwood, Wisconsin

Half of springs at Weyerhaeuser 1N, WI see their last 32°F night by May 9; only one in ten is past it by April 26, and one in ten still has one after May 27. Planting tender crops after May 16 leaves a 30% risk of a frost on them, after May 21 20%, and after May 27 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 September 29 in half of years, as early as September 14 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 11 days later, around October 10; in spring the one-in-ten date for 28°F is May 15, 12 days before the 32°F one. The freeze-free season lasts 140 days in a typical year, shorter than at 85% of the 182 Wisconsin stations; it reaches 160 days one year in ten and falls short of 119 one year in ten. On average 176 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 13 days longer, to about May 22, and return around September 21. Severe cold of 16°F or below comes every winter, usually between November 12 and March 31.

July is the warmest month at Weyerhaeuser 1N, WI, averaging 81°F by day and 58°F at night; January is the coldest at 23°F and 5°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 78% of years.

Warmth for growing adds up to 2,205 growing degree days a year (base 50°F), fewer than at 75% of the 182 Wisconsin stations. 32% of them (713) have built up by the end of June, and July adds the most, 593. Precipitation totals 34.2 inches a year, most in June (4.4") and least in January (0.9"); May to September bring 60% of it.

The nearest other station, Spooner Ag Res Stn, WI, 19 miles northwest of Birchwood, has a last frost 5 days later (May 14), a first frost 1 day earlier (September 28), a season 5 days shorter.

The first measurable snow (0.1 inch or more) in Birchwood usually arrives around November 3, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Couderay 7 W, WI, 10.4 miles away: half of years saw snow earlier, half later. Snow fell in 96% of those winters. The last 32°F night of spring typically comes 26 days after the last snow.

ZIP 54817 is 16 miles from Weyerhaeuser 1N, WI, which stands at 1,195 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 54819 (Bruce). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54817 in zone 4a, the band where the coldest night of the year averaged -30 to -25°F (-34.4 to -31.7°C) over 1991–2020; a zone describes winter lows, not frost dates.