Frost Dates for 61853 — Mahomet, Illinois

Half of springs at Champaign 9 SW, IL see their last 32°F night by April 23; only one in ten is past it by April 9, and one in ten still has one after May 9. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 9 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 13 in half of years, as early as September 28 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 10 days later, around October 23; in spring the one-in-ten date for 28°F is April 28, 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 191 days one year in ten and falls short of 149 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 11 days longer, to about May 4, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 27 and March 9.

July is the warmest month at Champaign 9 SW, IL, averaging 84°F by day and 62°F at night; January is the coldest at 33°F and 17°F. A freezing night is all but certain in every month from October 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 26% of years.

Warmth for growing adds up to 3,208 growing degree days a year (base 50°F), fewer than at 70% of the 158 Illinois stations. 37% of them (1,197) have built up by the end of June, and July adds the most, 708. Precipitation totals 39.7 inches a year, most in June (4.9") and least in February (2.0"); May to September bring 51% of it.

The nearest other station, Champaign 3S, IL, 12 miles southeast of Mahomet, has a last frost 8 days earlier (April 15), a first frost 11 days later (October 24), a season 20 days longer.

The first measurable snow (0.1 inch or more) in Mahomet usually arrives around December 4, and the last of the season around March 6. Those are the middle dates across the winters of 1991–2020 at Fisher, IL, 8.2 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 48 days after the last snow.

ZIP 61853 is 11 miles from Champaign 9 SW, IL, which stands at 700 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 61853 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.