Frost Dates for 61802 — Urbana, Illinois

Half of springs at Champaign 3S, IL see their last 32°F night by April 15; only one in ten is past it by April 1, and one in ten still has one after April 29. Planting tender crops after April 21 leaves a 30% risk of a frost on them, after April 24 20%, and after April 29 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 24 in half of years, as early as October 11 one year in ten, and holds off past November 5 one year in ten. A hard freeze of 28°F follows 9 days later, around November 2; in spring the one-in-ten date for 28°F is April 19, 10 days before the 32°F one. The freeze-free season lasts 190 days in a typical year, longer than at 66% of the 158 Illinois stations; it reaches 209 days one year in ten and falls short of 171 one year in ten. On average 120 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 11 days longer, to about April 26, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 1 and March 8.

July is the warmest month at Champaign 3S, IL, averaging 85°F by day and 65°F at night; January is the coldest at 34°F and 18°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month.

Warmth for growing adds up to 3,568 growing degree days a year (base 50°F), more than at 56% of the 158 Illinois stations. 36% of them (1,287) have built up by the end of June, and July adds the most, 781. Precipitation totals 41.0 inches a year, most in May (4.8") and least in February (2.2"); May to September bring 51% of it.

The nearest other station, Champaign Willard Airport, IL, 8 miles southwest of Urbana, has a last frost 4 days later (April 19), a first frost 7 days earlier (October 17), a season 10 days shorter.

The first measurable snow (0.1 inch or more) in Urbana usually arrives around December 1, and the last of the season around March 14. Those are the middle dates across the winters of 1991–2020 at Champaign 3S, IL, 4.3 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 32 days after the last snow.

ZIP 61802 is 4 miles from Champaign 3S, IL, which stands at 721 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station; its figures are presented in full for 61820 (Champaign). The 2023 USDA Plant Hardiness Zone Map lists ZIP 61802 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.