Frost Dates for 62615 — Auburn, Illinois

Half of springs at Virden, IL see their last 32°F night by April 7; only one in ten is past it by March 22, and one in ten still has one after April 21. Planting tender crops after April 13 leaves a 30% risk of a frost on them, after April 17 20%, and after April 21 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 29 in half of years, as early as October 16 one year in ten, and holds off past November 11 one year in ten. A hard freeze of 28°F follows 9 days later, around November 7; in spring the one-in-ten date for 28°F is April 12, 9 days before the 32°F one. The freeze-free season lasts 205 days in a typical year, longer than at 96% of the 158 Illinois stations; it reaches 225 days one year in ten and falls short of 185 one year in ten. On average 101 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 19, and return around October 19. Severe cold of 16°F or below comes every winter, usually between December 7 and March 1.

July is the warmest month at Virden, IL, averaging 87°F by day and 68°F at night; January is the coldest at 36°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 69% of years.

Warmth for growing adds up to 4,040 growing degree days a year (base 50°F), more than at 85% of the 158 Illinois stations. 37% of them (1,502) have built up by the end of June, and July adds the most, 845. Precipitation totals 38.4 inches a year, most in June (4.3") and least in January (2.0"); May to September bring 48% of it.

The nearest other station, Springfield #2, IL, 15 miles north of Auburn, has a last frost 8 days later (April 15), a first frost 7 days earlier (October 22), a season 17 days shorter.

The first measurable snow (0.1 inch or more) in Auburn usually arrives around December 7, and the last of the season around March 3. Those are the middle dates across the winters of 1991–2020 at Virden, IL, 5.8 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 35 days after the last snow.

ZIP 62615 is 6 miles from Virden, IL, which stands at 675 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62615 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.