Frost Dates for 54165 — Seymour, Wisconsin

Half of springs at Green Bay WFO, WI see their last 32°F night by May 1; only one in ten is past it by April 19, and one in ten still has one after May 16. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 12 20%, and after May 16 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 11 in half of years, as early as September 26 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 14 days later, around October 25; in spring the one-in-ten date for 28°F is May 4, 12 days before the 32°F one. The freeze-free season lasts 160 days in a typical year, longer than at 60% of the 182 Wisconsin stations; it reaches 182 days one year in ten and falls short of 140 one year in ten. On average 151 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 13 days longer, to about May 14, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 23 and March 22.

July is the warmest month at Green Bay WFO, WI, averaging 81°F by day and 60°F at night; January is the coldest at 25°F and 10°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 52% of years.

Warmth for growing adds up to 2,353 growing degree days a year (base 50°F), fewer than at 60% of the 182 Wisconsin stations. 31% of them (736) have built up by the end of June, and July adds the most, 626. Precipitation totals 31.7 inches a year, most in June (4.1") and least in February (1.2"); May to September bring 56% of it.

The nearest other station, Green Bay, WI, 10 miles east of Seymour, has a last frost 1 day earlier (April 30), a first frost 2 days earlier (October 9), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Seymour usually arrives around November 19, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Green Bay WFO, WI, 9.9 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 19 days after the last snow.

ZIP 54165 is 10 miles from Green Bay WFO, WI, which stands at 682 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 54165 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.