Frost Dates for 53072 — Pewaukee, Wisconsin

Half of springs at Brookfield Wwtp, WI see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 15. Planting tender crops after May 5 leaves a 30% risk of a frost on them, after May 8 20%, and after May 15 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 14 in half of years, as early as September 28 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 11 days later, around October 25; in spring the one-in-ten date for 28°F is May 3, 12 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, longer than at 71% of the 182 Wisconsin stations; it reaches 184 days one year in ten and falls short of 144 one year in ten. On average 149 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 3. Severe cold of 16°F or below comes every winter, usually between November 23 and March 19.

July is the warmest month at Brookfield Wwtp, WI, averaging 81°F by day and 61°F at night; January is the coldest at 28°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 August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 47% of years.

Warmth for growing adds up to 2,550 growing degree days a year (base 50°F), more than at 65% of the 182 Wisconsin stations. 31% of them (795) have built up by the end of June, and July adds the most, 660. Precipitation totals 36.0 inches a year, most in June (4.8") and least in January (1.6"); May to September bring 55% of it.

The nearest other station, Waukesha Wwtp, WI, 5 miles south of Pewaukee, has a last frost 1 day later (May 1), a first frost 1 day earlier (October 13), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Pewaukee usually arrives around November 24, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Waukesha Wwtp, WI, 5 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 36 days after the last snow.

ZIP 53072 is 5 miles from Brookfield Wwtp, WI, which stands at 830 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 53072 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.