Frost Dates for 54414 — Birnamwood, Wisconsin

Half of springs at Stockbridge-Munsee Rsvn, WI see their last 32°F night by May 13; only one in ten is past it by April 29, and one in ten still has one after May 26. Planting tender crops after May 19 leaves a 30% risk of a frost on them, after May 22 20%, and after May 26 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 September 30 in half of years, as early as September 17 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 12 days later, around October 12; in spring the one-in-ten date for 28°F is May 16, 10 days before the 32°F one. The freeze-free season lasts 141 days in a typical year, shorter than at 82% of the 182 Wisconsin stations; it reaches 159 days one year in ten and falls short of 121 one year in ten. On average 178 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 25, and return around September 21. Severe cold of 16°F or below comes every winter, usually between November 16 and April 1.

July is the warmest month at Stockbridge-Munsee Rsvn, WI, averaging 78°F by day and 56°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 85% of years.

Warmth for growing adds up to 1,974 growing degree days a year (base 50°F), fewer than at 88% of the 182 Wisconsin stations. 32% of them (628) have built up by the end of June, and July adds the most, 536.

The nearest other station, Rosholt 9 NNE, WI, 14 miles south of Birnamwood, has a last frost 7 days earlier (May 6), a first frost 5 days later (October 5), a season 9 days longer.

The first measurable snow (0.1 inch or more) in Birnamwood usually arrives around November 6, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Rosholt 9 NNE, WI, 14.5 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 31 days after the last snow.

ZIP 54414 is 14 miles from Stockbridge-Munsee Rsvn, WI, which stands at 1,050 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 54414 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.