Frost Dates for 61443 — Kewanee, Illinois

Half of springs at Kewanee 1 E, IL see their last 32°F night by April 24; only one in ten is past it by April 10, and one in ten still has one after May 8. Planting tender crops after April 30 leaves a 30% risk of a frost on them, after May 3 20%, and after May 8 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 17 in half of years, as early as October 3 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 11 days later, around October 28; in spring the one-in-ten date for 28°F is April 29, 9 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, shorter than at 75% of the 158 Illinois stations; it reaches 195 days one year in ten and falls short of 155 one year in ten. On average 141 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 10 days longer, to about May 4, and return around October 6. Severe cold of 16°F or below comes every winter, usually between November 25 and March 12.

July is the warmest month at Kewanee 1 E, IL, averaging 84°F by day and 63°F at night; January is the coldest at 30°F and 14°F. A freezing night is all but certain in every month from October 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 27% of years.

Warmth for growing adds up to 3,117 growing degree days a year (base 50°F), fewer than at 77% of the 158 Illinois stations. 35% of them (1,106) have built up by the end of June, and July adds the most, 730. Precipitation totals 39.8 inches a year, most in May (5.1") and least in January (1.9"); May to September bring 54% of it.

The nearest other station, Galva, IL, 8 miles southwest of Kewanee, has a last frost 2 days later (April 26), a first frost 5 days earlier (October 12), a season 9 days shorter.

The first measurable snow (0.1 inch or more) in Kewanee usually arrives around December 1, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Kewanee 1 E, IL, 1.5 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 34 days after the last snow.

ZIP 61443 is 2 miles from Kewanee 1 E, IL, which stands at 780 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 61443 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.