Frost Dates for 53070 — Oostburg, Wisconsin

Half of springs at Hingham Wwtp, WI see their last 32°F night by May 3; only one in ten is past it by April 18, and one in ten still has one after May 18. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 13 20%, and after May 18 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 16 in half of years, as early as October 2 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 12 days later, around October 28; in spring the one-in-ten date for 28°F is May 5, 13 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 184 days one year in ten and falls short of 145 one year in ten. On average 148 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 15, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 25 and March 19.

July is the warmest month at Hingham Wwtp, WI, averaging 80°F by day and 61°F at night; January is the coldest at 27°F and 12°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 57% of years.

Warmth for growing adds up to 2,387 growing degree days a year (base 50°F), fewer than at 55% of the 182 Wisconsin stations. 30% of them (707) have built up by the end of June, and July adds the most, 635. Precipitation totals 34.6 inches a year, most in June (4.3") and least in January (1.7"); May to September bring 52% of it.

The nearest other station, Belgium Wwtp, WI, 8 miles south of Oostburg, has a last frost 2 days later (May 5), a first frost 4 days earlier (October 12), a season 6 days shorter.

The first measurable snow (0.1 inch or more) in Oostburg usually arrives around November 24, and the last of the season around April 2. Those are the middle dates across the winters of 1991–2020 at Oostburg, WI, 0.6 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 31 days after the last snow.

ZIP 53070 is 5 miles from Hingham Wwtp, WI, which stands at 763 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 53070 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.