Frost Dates for 61559 — Princeville, Illinois

Half of springs at Princeville, IL see their last 32°F night by April 22; only one in ten is past it by April 8, and one in ten still has one after May 6. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 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 14 in half of years, as early as September 29 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 12 days later, around October 26; in spring the one-in-ten date for 28°F is April 30, 6 days before the 32°F one. The freeze-free season lasts 174 days in a typical year, shorter than at 76% of the 158 Illinois stations; it reaches 195 days one year in ten and falls short of 153 one year in ten. On average 143 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 2, and return around October 4. Severe cold of 16°F or below comes every winter, usually between November 25 and March 14.

July is the warmest month at Princeville, IL, averaging 86°F by day and 63°F at night; January is the coldest at 33°F and 15°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 25% of years.

Warmth for growing adds up to 3,345 growing degree days a year (base 50°F), fewer than at 61% of the 158 Illinois stations. 37% of them (1,230) have built up by the end of June, and July adds the most, 755. Precipitation totals 39.0 inches a year, most in May (5.1") and least in February (1.9"); May to September bring 54% of it.

The nearest other station, Peoria Gtr Peoria Airport, IL, 19 miles south of Princeville, has a last frost 6 days earlier (April 16), a first frost 9 days later (October 23), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Princeville usually arrives around December 1, and the last of the season around March 17. Those are the middle dates across the winters of 1991–2020 at Princeville, IL, 0.8 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 36 days after the last snow.

ZIP 61559 is under a mile from Princeville, IL, which stands at 750 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 61525 (Dunlap). The 2023 USDA Plant Hardiness Zone Map lists ZIP 61559 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.