Frost Dates for 54871 — Shell Lake, Wisconsin

Half of springs at Spooner Ag Res Stn, WI see their last 32°F night by May 14; only one in ten is past it by April 30, and one in ten still has one after May 29. Planting tender crops after May 21 leaves a 30% risk of a frost on them, after May 25 20%, and after May 29 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 30% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 28 in half of years, as early as September 14 one year in ten, and holds off past October 11 one year in ten. A hard freeze of 28°F follows 9 days later, around October 7; in spring the one-in-ten date for 28°F is May 19, 10 days before the 32°F one. The freeze-free season lasts 135 days in a typical year, shorter than at 90% of the 182 Wisconsin stations; it reaches 156 days one year in ten and falls short of 113 one year in ten. On average 171 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 26, and return around September 19. Severe cold of 16°F or below comes every winter, usually between November 9 and April 4.

July is the warmest month at Spooner Ag Res Stn, WI, averaging 80°F by day and 58°F at night; January is the coldest at 21°F and 1°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 87% of years.

Warmth for growing adds up to 2,182 growing degree days a year (base 50°F), fewer than at 77% of the 182 Wisconsin stations. 32% of them (703) have built up by the end of June, and July adds the most, 590. Precipitation totals 31.7 inches a year, most in June (4.2") and least in January (0.8"); May to September bring 62% of it.

The nearest other station, Cumberland, WI, 15 miles south of Shell Lake, has a last frost 9 days earlier (May 5), a first frost 6 days later (October 4), a season 17 days longer.

The first measurable snow (0.1 inch or more) in Shell Lake usually arrives around November 3, and the last of the season around April 16. Those are the middle dates across the winters of 1991–2020 at Spooner Ag Res Stn, WI, 7.5 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 28 days after the last snow.

ZIP 54871 is 8 miles from Spooner Ag Res Stn, WI, which stands at 1,100 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 54801 (Spooner). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54871 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.