Frost Dates for 54479 — Spencer, Wisconsin

Half of springs at Marshfield Municipal Airport, WI see their last 32°F night by May 5; only one in ten is past it by April 22, and one in ten still has one after May 20. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 16 20%, and after May 20 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 October 5 in half of years, as early as September 21 one year in ten, and holds off past October 18 one year in ten. A hard freeze of 28°F follows 11 days later, around October 16; in spring the one-in-ten date for 28°F is May 10, 10 days before the 32°F one. The freeze-free season lasts 152 days in a typical year, shorter than at 59% of the 182 Wisconsin stations; it reaches 171 days one year in ten and falls short of 133 one year in ten. On average 162 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 17, and return around September 26. Severe cold of 16°F or below comes every winter, usually between November 17 and March 28.

July is the warmest month at Marshfield Municipal Airport, WI, averaging 80°F by day and 58°F at night; January is the coldest at 23°F and 7°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 67% of years.

Warmth for growing adds up to 2,228 growing degree days a year (base 50°F), fewer than at 73% of the 182 Wisconsin stations. 33% of them (731) have built up by the end of June, and July adds the most, 589. Precipitation totals 24.8 inches a year, most in June (3.8") and least in February (0.5"); May to September bring 65% of it.

The nearest other station, Marshfield Exp Farm, WI, 13 miles southeast of Spencer, has the same 50% last-frost date, the same first-frost date, a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Spencer usually arrives around November 8, and the last of the season around April 15. Those are the middle dates across the winters of 1991–2020 at Stratford 1 NW, WI, 12.4 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 20 days after the last snow.

ZIP 54479 is 11 miles from Marshfield Municipal Airport, WI, which stands at 1,255 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 54449 (Marshfield). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54479 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.