Frost Dates for 61032 — Freeport, Illinois

Half of springs at Freeport Waste Wtp, IL see their last 32°F night by April 26; only one in ten is past it by April 11, and one in ten still has one after May 11. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 6 20%, and after May 11 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 13 in half of years, as early as September 30 one year in ten, and holds off past October 26 one year in ten. A hard freeze of 28°F follows 11 days later, around October 24; in spring the one-in-ten date for 28°F is April 30, 11 days before the 32°F one. The freeze-free season lasts 169 days in a typical year, shorter than at 90% of the 158 Illinois stations; it reaches 188 days one year in ten and falls short of 151 one year in ten. On average 148 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 10 days longer, to about May 6, and return around October 3. Severe cold of 16°F or below comes every winter, usually between November 24 and March 14.

July is the warmest month at Freeport Waste Wtp, IL, averaging 82°F by day and 62°F at night; January is the coldest at 28°F and 11°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 2,811 growing degree days a year (base 50°F), fewer than at 93% of the 158 Illinois stations. 34% of them (967) have built up by the end of June, and July adds the most, 693. Precipitation totals 38.6 inches a year, most in June (5.3") and least in January (1.6"); May to September bring 58% of it.

The nearest other station, Polo 5NW, IL, 18 miles south of Freeport, has a last frost 3 days later (April 29), a first frost 6 days earlier (October 7), a season 8 days shorter.

The first measurable snow (0.1 inch or more) in Freeport usually arrives around November 26, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Freeport Waste Wtp, IL, 1.5 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 32 days after the last snow.

ZIP 61032 is 2 miles from Freeport Waste Wtp, IL, which stands at 750 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 61032 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.