Frost Dates for 60044 — Lake Bluff, Illinois

Half of springs at Waukegan, IL see their last 32°F night by April 30; only one in ten is past it by April 15, 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 7 20%, and after May 14 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 82% of the 158 Illinois stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 19 in half of years, as early as September 30 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 11 days later, around October 30; in spring the one-in-ten date for 28°F is May 3, 11 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, shorter than at 87% of the 158 Illinois stations; it reaches 190 days one year in ten and falls short of 150 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 8 days longer, to about May 8, and return around October 8. Severe cold of 16°F or below comes every winter, usually between November 30 and March 16.

July is the warmest month at Waukegan, IL, averaging 82°F by day and 63°F at night; January is the coldest at 30°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 August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 44% of years.

Warmth for growing adds up to 2,748 growing degree days a year (base 50°F), fewer than at 96% of the 158 Illinois stations. 30% of them (827) have built up by the end of June, and July adds the most, 693.

The nearest other station, Chicago Waukegan Regional Airport, IL, 9 miles north of Lake Bluff, has the same 50% last-frost date, a first frost 2 days later (October 21), a season 3 days longer.

The first measurable snow (0.1 inch or more) in Lake Bluff usually arrives around November 21, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at Chicago Botanic Garden, IL, 10.9 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 35 days after the last snow.

ZIP 60044 is 5 miles from Waukegan, IL, which stands at 700 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 60085 (Waukegan). The 2023 USDA Plant Hardiness Zone Map lists ZIP 60044 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.