Frost Dates for 62839 — Flora, Illinois

Half of springs at Flora, IL see their last 32°F night by April 9; only one in ten is past it by March 29, and one in ten still has one after April 23. Planting tender crops after April 15 leaves a 30% risk of a frost on them, after April 19 20%, and after April 23 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 24 in half of years, as early as October 11 one year in ten, and holds off past November 6 one year in ten. A hard freeze of 28°F follows 10 days later, around November 3; in spring the one-in-ten date for 28°F is April 14, 9 days before the 32°F one. The freeze-free season lasts 198 days in a typical year, longer than at 84% of the 158 Illinois stations; it reaches 217 days one year in ten and falls short of 177 one year in ten. On average 109 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 21, and return around October 15. Severe cold of 16°F or below comes every winter, usually between December 6 and February 28.

July is the warmest month at Flora, IL, averaging 89°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 82% of years.

Warmth for growing adds up to 4,018 growing degree days a year (base 50°F), more than at 84% of the 158 Illinois stations. 38% of them (1,516) have built up by the end of June, and July adds the most, 849. Precipitation totals 48.0 inches a year, most in June (5.9") and least in February (2.5"); May to September bring 46% of it.

The nearest other station, Flora 5 NW, IL, 6 miles northwest of Flora, has a last frost 1 day later (April 10), a first frost 1 day earlier (October 23), a season 2 days shorter.

The first measurable snow (0.1 inch or more) in Flora usually arrives around December 13, and the last of the season around February 26. Those are the middle dates across the winters of 1991–2020 at Flora 5 NW, IL, 5.5 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 42 days after the last snow.

ZIP 62839 is under a mile from Flora, IL, which stands at 481 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 62839 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.