Frost Dates for 60087 — Waukegan, Illinois

Half of springs at Chicago Waukegan Regional Airport, IL see their last 32°F night by April 30; only one in ten is past it by April 14, and one in ten still has one after May 16. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 10 20%, and after May 16 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 22% of the 158 Illinois stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 21 in half of years, as early as October 5 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 11 days later, around November 1; in spring the one-in-ten date for 28°F is May 2, 14 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, shorter than at 81% of the 158 Illinois stations; it reaches 194 days one year in ten and falls short of 152 one year in ten. On average 132 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 12, and return around October 10. Severe cold of 16°F or below comes every winter, usually between November 28 and March 14.

July is the warmest month at Chicago Waukegan Regional Airport, IL, averaging 81°F by day and 62°F at night; January is the coldest at 31°F and 16°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 46% of years.

Warmth for growing adds up to 2,670 growing degree days a year (base 50°F), fewer than at 99% of the 158 Illinois stations. 30% of them (798) have built up by the end of June, and July adds the most, 669. Precipitation totals 35.5 inches a year, most in June (4.5") and least in January (1.4"); May to September bring 54% of it.

The nearest other station, Waukegan, IL, 4 miles south of Waukegan, has the same 50% last-frost date, a first frost 2 days earlier (October 19), a season 3 days shorter.

The first measurable snow (0.1 inch or more) in Waukegan usually arrives around November 16, and the last of the season around April 4. Those are the middle dates across the winters of 1991–2020 at Lake Villa 2NE, IL, 10.1 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 26 days after the last snow.

ZIP 60087 is under a mile from Chicago Waukegan Regional Airport, IL, which stands at 727 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station; its figures are presented in full for 60099 (Zion). The 2023 USDA Plant Hardiness Zone Map lists ZIP 60087 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.