Frost Dates for 60035 — Highland Park, Illinois

Half of springs at Chicago Botanic Garden, IL see their last 32°F night by April 26; only one in ten is past it by April 11, and one in ten still has one after May 11. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 6 20%, and after May 11 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 54% 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 April 28, 13 days before the 32°F one. The freeze-free season lasts 176 days in a typical year, shorter than at 73% of the 158 Illinois stations; it reaches 197 days one year in ten and falls short of 155 one year in ten. On average 128 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 8, and return around October 10. Severe cold of 16°F or below comes every winter, usually between December 1 and March 11.

July is the warmest month at Chicago Botanic Garden, IL, averaging 84°F by day and 63°F at night; January is the coldest at 32°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 35% of years.

Warmth for growing adds up to 2,963 growing degree days a year (base 50°F), fewer than at 86% of the 158 Illinois stations. 31% of them (910) have built up by the end of June, and July adds the most, 727. Precipitation totals 39.5 inches a year, most in May (4.8") and least in February (2.0"); May to September bring 52% of it.

The nearest other station, Chicago Palwaukee Airport, IL, 6 miles southwest of Highland Park, has a last frost 7 days earlier (April 19), a first frost 5 days later (October 26), a season 14 days longer.

The first measurable snow (0.1 inch or more) in Highland Park 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, 3.1 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 31 days after the last snow.

ZIP 60035 is 3 miles from Chicago Botanic Garden, IL, which stands at 630 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 16 other ZIP codes share the station; its figures are presented in full for 60626 (Chicago). The 2023 USDA Plant Hardiness Zone Map lists ZIP 60035 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.