Frost Dates for 54667 — Westby, Wisconsin

Half of springs at Viroqua, WI see their last 32°F night by May 7; only one in ten is past it by April 23, and one in ten still has one after May 21. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 17 20%, and after May 21 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 2 in half of years, as early as September 18 one year in ten, and holds off past October 17 one year in ten. A hard freeze of 28°F follows 11 days later, around October 13; in spring the one-in-ten date for 28°F is May 11, 10 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 69% of the 182 Wisconsin stations; it reaches 166 days one year in ten and falls short of 130 one year in ten. On average 165 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 9 days longer, to about May 16, and return around September 25. Severe cold of 16°F or below comes every winter, usually between November 13 and March 29.

July is the warmest month at Viroqua, WI, averaging 79°F by day and 59°F at night; January is the coldest at 23°F and 6°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 70% of years.

Warmth for growing adds up to 2,227 growing degree days a year (base 50°F), fewer than at 74% of the 182 Wisconsin stations. 33% of them (725) have built up by the end of June, and July adds the most, 590. Precipitation totals 38.1 inches a year, most in June (5.7") and least in February (1.1"); May to September bring 62% of it.

The nearest other station, Cashton, WI, 7 miles northeast of Westby, has a last frost 10 days earlier (April 27), a first frost 12 days later (October 14), a season 22 days longer.

The first measurable snow (0.1 inch or more) in Westby usually arrives around November 11, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Westby 3ENE, WI, 2.7 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 25 days after the last snow.

ZIP 54667 is 7 miles from Viroqua, WI, which stands at 1,255 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 54665 (Viroqua). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54667 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.