Frost Dates for 62466 — Sumner, Illinois

Half of springs at Lawrenceville 2WSW, IL see their last 32°F night by April 12; only one in ten is past it by March 31, and one in ten still has one after April 30. Planting tender crops after April 19 leaves a 30% risk of a frost on them, after April 23 20%, and after April 30 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 92% of the 158 Illinois stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 25 in half of years, as early as October 12 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 3; in spring the one-in-ten date for 28°F is April 17, 13 days before the 32°F one. The freeze-free season lasts 193 days in a typical year, longer than at 77% of the 158 Illinois stations; it reaches 213 days one year in ten and falls short of 172 one year in ten. On average 98 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 12 days longer, to about April 24, and return around October 16. Severe cold of 16°F or below comes every winter, usually between December 7 and March 1.

July is the warmest month at Lawrenceville 2WSW, IL, averaging 88°F by day and 66°F at night; January is the coldest at 39°F and 21°F. A freezing night is all but certain in every month from November to March (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, April still brings one in 89% of years.

Warmth for growing adds up to 3,971 growing degree days a year (base 50°F), more than at 82% of the 158 Illinois stations. 37% of them (1,476) have built up by the end of June, and July adds the most, 835. Precipitation totals 46.8 inches a year, most in May (5.3") and least in February (2.7"); May to September bring 46% of it.

The nearest other station, Olney 2S, IL, 13 miles west of Sumner, has a last frost 3 days later (April 15), a first frost 2 days earlier (October 23), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Sumner usually arrives around December 7, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Lawrenceville 2WSW, IL, 7.1 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 39 days after the last snow.

ZIP 62466 is 7 miles from Lawrenceville 2WSW, IL, which stands at 451 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 62439 (Lawrenceville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 62466 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.