Frost Dates for 62012 — Brighton, Illinois

Half of springs at Jerseyville 2 SW, IL see their last 32°F night by April 14; 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 21 leaves a 30% risk of a frost on them, after April 25 20%, and after April 30 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 19 in half of years, as early as October 7 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 11 days later, around October 30; in spring the one-in-ten date for 28°F is April 19, 11 days before the 32°F one. The freeze-free season lasts 187 days in a typical year, longer than at 54% of the 158 Illinois stations; it reaches 206 days one year in ten and falls short of 168 one year in ten. On average 118 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 26, and return around October 11. Severe cold of 16°F or below comes every winter, usually between December 3 and March 5.

July is the warmest month at Jerseyville 2 SW, IL, averaging 87°F by day and 66°F at night; January is the coldest at 36°F and 19°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 88% of years.

Warmth for growing adds up to 3,714 growing degree days a year (base 50°F), more than at 68% of the 158 Illinois stations. 37% of them (1,367) have built up by the end of June, and July adds the most, 814. Precipitation totals 42.4 inches a year, most in May (5.3") and least in February (2.3"); May to September bring 47% of it.

The nearest other station, Alton - Melvin Price L&D, IL, 12 miles south of Brighton and 225 feet lower, has a last frost 10 days earlier (April 4), a first frost 17 days later (November 5), a season 27 days longer.

The first measurable snow (0.1 inch or more) in Brighton usually arrives around December 3, and the last of the season around March 10. Those are the middle dates across the winters of 1991–2020 at Medora 1 S, IL, 8.1 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 35 days after the last snow.

ZIP 62012 is 12 miles from Jerseyville 2 SW, IL, which stands at 630 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 62052 (Jerseyville). The 2023 USDA Plant Hardiness Zone Map lists ZIP 62012 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.