Frost Dates for 53074 — Port Washington, Wisconsin

Half of springs at Port Washington, WI see their last 32°F night by April 27; only one in ten is past it by April 11, and one in ten still has one after May 14. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 8 20%, and after May 14 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 90% of the 182 Wisconsin stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 22 in half of years, as early as October 6 one year in ten, and holds off past November 4 one year in ten. A hard freeze of 28°F follows 11 days later, around November 2; in spring the one-in-ten date for 28°F is April 30, 14 days before the 32°F one. The freeze-free season lasts 176 days in a typical year, longer than at 90% of the 182 Wisconsin stations; it reaches 196 days one year in ten and falls short of 154 one year in ten. On average 133 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 10, and return around October 10. Severe cold of 16°F or below comes every winter, usually between November 29 and March 15.

July is the warmest month at Port Washington, WI, averaging 79°F by day and 62°F at night; January is the coldest at 31°F and 15°F. A freezing night is all but certain in every month from November 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 39% of years.

Warmth for growing adds up to 2,305 growing degree days a year (base 50°F), fewer than at 65% of the 182 Wisconsin stations. 25% of them (569) have built up by the end of June, and July adds the most, 623. Precipitation totals 34.0 inches a year, most in June (4.2") and least in February (1.5"); May to September bring 54% of it.

The nearest other station, Saukville Wwtp, WI, 4 miles southwest of Port Washington and 172 feet higher, has a last frost 8 days later (May 5), a first frost 11 days earlier (October 11), a season 18 days shorter.

The first measurable snow (0.1 inch or more) in Port Washington usually arrives around December 2, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Port Washington, WI, 1 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 33 days after the last snow.

ZIP 53074 is 1 mile from Port Washington, WI, which stands at 594 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 53074 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.