Frost Dates for 54902 — Oshkosh, Wisconsin

Half of springs at Oshkosh Wittman Airport, WI see their last 32°F night by April 30; only one in ten is past it by April 15, and one in ten still has one after May 13. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 8 20%, and after May 13 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 84% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 13 in half of years, as early as September 29 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 13 days later, around October 26; in spring the one-in-ten date for 28°F is May 2, 11 days before the 32°F one. The freeze-free season lasts 165 days in a typical year, longer than at 74% of the 182 Wisconsin stations; it reaches 185 days one year in ten and falls short of 146 one year in ten. On average 146 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 10 days longer, to about May 10, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 24 and March 19.

July is the warmest month at Oshkosh Wittman Airport, WI, averaging 81°F by day and 61°F at night; January is the coldest at 26°F and 11°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 45% of years.

Warmth for growing adds up to 2,560 growing degree days a year (base 50°F), more than at 65% of the 182 Wisconsin stations. 32% of them (829) have built up by the end of June, and July adds the most, 659. Precipitation totals 30.6 inches a year, most in June (4.7") and least in February (0.8"); May to September bring 59% of it.

The nearest other station, Oshkosh, WI, 2 miles north of Oshkosh, has a last frost 6 days earlier (April 24), a first frost 7 days later (October 20), a season 13 days longer.

The first measurable snow (0.1 inch or more) in Oshkosh usually arrives around November 24, and the last of the season around April 7. Those are the middle dates across the winters of 1991–2020 at Oshkosh, WI, 2.3 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 23 days after the last snow.

ZIP 54902 is under a mile from Oshkosh Wittman Airport, WI, which stands at 782 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 54902 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.