Frost Dates for 54615 — Black River Falls, Wisconsin

Half of springs at Blair, WI see their last 32°F night by May 9; only one in ten is past it by April 28, and one in ten still has one after May 23. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 18 20%, and after May 23 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 1 in half of years, as early as September 18 one year in ten, and holds off past October 11 one year in ten. A hard freeze of 28°F follows 7 days later, around October 8; in spring the one-in-ten date for 28°F is May 13, 10 days before the 32°F one. The freeze-free season lasts 143 days in a typical year, shorter than at 80% of the 182 Wisconsin stations; it reaches 161 days one year in ten and falls short of 125 one year in ten. On average 177 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 20, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 9 and March 31.

July is the warmest month at Blair, WI, averaging 81°F by day and 59°F at night; January is the coldest at 24°F and 4°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 83% of years.

Warmth for growing adds up to 2,335 growing degree days a year (base 50°F), fewer than at 62% of the 182 Wisconsin stations. 33% of them (773) have built up by the end of June, and July adds the most, 621. Precipitation totals 35.6 inches a year, most in June (5.0") and least in January (1.0"); May to September bring 64% of it.

The nearest other station, Neillsville 3ESE, WI, 22 miles northeast of Black River Falls and 225 feet higher, has a last frost 1 day later (May 10), the same first-frost date, a season 1 day longer.

The first measurable snow (0.1 inch or more) in Black River Falls usually arrives around November 23, and the last of the season around April 11. Those are the middle dates across the winters of 1991–2020 at Black Rvr Falls Sewage, WI, 2.8 miles away: half of years saw snow earlier, half later. Snow fell in 83% of those winters. The last 32°F night of spring typically comes 28 days after the last snow.

ZIP 54615 is 21 miles from Blair, WI, which stands at 855 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54615 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.