Frost Dates for 54963 — Omro, Wisconsin

Half of springs at Berlin Wwtp, 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 11 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 8 in half of years, as early as September 24 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 12 days later, around October 20; 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 158 days in a typical year, longer than at 56% of the 182 Wisconsin stations; it reaches 176 days one year in ten and falls short of 139 one year in ten. On average 161 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 11 days longer, to about May 12, and return around September 28. Severe cold of 16°F or below comes every winter, usually between November 20 and March 24.

July is the warmest month at Berlin Wwtp, WI, averaging 81°F by day and 60°F at night; January is the coldest at 25°F and 8°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 53% of years.

Warmth for growing adds up to 2,428 growing degree days a year (base 50°F), more than at 50% of the 182 Wisconsin stations. 32% of them (787) have built up by the end of June, and July adds the most, 637. Precipitation totals 35.2 inches a year, most in July (4.5") and least in February (1.3"); May to September bring 57% of it.

The nearest other station, Oshkosh, WI, 10 miles east of Omro, has a last frost 7 days earlier (April 24), a first frost 12 days later (October 20), a season 20 days longer.

The first measurable snow (0.1 inch or more) in Omro usually arrives around November 23, and the last of the season around April 9. Those are the middle dates across the winters of 1991–2020 at Berlin Wwtp, WI, 9.6 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 22 days after the last snow.

ZIP 54963 is 10 miles from Berlin Wwtp, WI, which stands at 766 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 54923 (Berlin). The 2023 USDA Plant Hardiness Zone Map lists ZIP 54963 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.