Frost Dates for 60556 — Waterman, Illinois

Half of springs at Shabbona 5 NNE, IL see their last 32°F night by April 28; only one in ten is past it by April 14, and one in ten still has one after May 13. Planting tender crops after May 4 leaves a 30% risk of a frost on them, after May 8 20%, and after May 13 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 10 in half of years, as early as September 26 one year in ten, and holds off past October 23 one year in ten. A hard freeze of 28°F follows 11 days later, around October 21; in spring the one-in-ten date for 28°F is May 4, 9 days before the 32°F one. The freeze-free season lasts 163 days in a typical year, shorter than at 96% of the 158 Illinois stations; it reaches 183 days one year in ten and falls short of 143 one year in ten. On average 144 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 8, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 21 and March 13.

July is the warmest month at Shabbona 5 NNE, IL, averaging 82°F by day and 61°F at night; January is the coldest at 28°F and 13°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 39% of years.

Warmth for growing adds up to 2,709 growing degree days a year (base 50°F), fewer than at 97% of the 158 Illinois stations. 36% of them (964) have built up by the end of June, and July adds the most, 651. Precipitation totals 37.5 inches a year, most in May (4.6") and least in January (1.7"); May to September bring 54% of it.

The nearest other station, De Kalb, IL, 11 miles north of Waterman, has a last frost 4 days earlier (April 24), a first frost 8 days later (October 18), a season 14 days longer.

The first measurable snow (0.1 inch or more) in Waterman usually arrives around November 30, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Shabbona 3S, IL, 5.2 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 60556 is 7 miles from Shabbona 5 NNE, IL, which stands at 861 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 60556 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.