Frost Dates for 61085 — Stockton, Illinois

Half of springs at Stockton 3 NNE, IL see their last 32°F night by April 27; only one in ten is past it by April 12, and one in ten still has one after May 12. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 12 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 9 in half of years, as early as September 26 one year in ten, and holds off past October 23 one year in ten. A hard freeze of 28°F follows 12 days later, around October 21; in spring the one-in-ten date for 28°F is May 2, 10 days before the 32°F one. The freeze-free season lasts 165 days in a typical year, shorter than at 94% of the 158 Illinois stations; it reaches 184 days one year in ten and falls short of 145 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 9 days longer, to about May 6, and return around September 29. Severe cold of 16°F or below comes every winter, usually between November 22 and March 16.

July is the warmest month at Stockton 3 NNE, IL, averaging 82°F by day and 61°F at night; January is the coldest at 28°F and 12°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 36% of years.

Warmth for growing adds up to 2,807 growing degree days a year (base 50°F), fewer than at 94% of the 158 Illinois stations. 36% of them (997) have built up by the end of June, and July adds the most, 666. Precipitation totals 38.6 inches a year, most in June (5.7") and least in January (1.2"); May to September bring 59% of it.

The nearest other station, Mt Carroll, IL, 18 miles south of Stockton and 330 feet lower, has a last frost 5 days later (May 2), a first frost 2 days earlier (October 7), a season 11 days shorter.

The first measurable snow (0.1 inch or more) in Stockton usually arrives around November 16, and the last of the season around April 1. Those are the middle dates across the winters of 1991–2020 at Stockton 3 NNE, IL, 3.8 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 26 days after the last snow.

ZIP 61085 is 4 miles from Stockton 3 NNE, IL, which stands at 970 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 61048 (Lena). The 2023 USDA Plant Hardiness Zone Map lists ZIP 61085 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.