Frost Dates for 60450 — Morris, Illinois

Half of springs at Morris 1 NW, IL see their last 32°F night by April 20; only one in ten is past it by April 6, and one in ten still has one after May 6. Planting tender crops after April 27 leaves a 30% risk of a frost on them, after April 30 20%, and after May 6 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 23 in half of years, as early as October 9 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 9 days later, around November 1; in spring the one-in-ten date for 28°F is April 24, 12 days before the 32°F one. The freeze-free season lasts 184 days in a typical year, shorter than at 51% of the 158 Illinois stations; it reaches 204 days one year in ten and falls short of 163 one year in ten. On average 127 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 April 30, and return around October 12. Severe cold of 16°F or below comes every winter, usually between November 29 and March 10.

July is the warmest month at Morris 1 NW, IL, averaging 85°F by day and 65°F at night; January is the coldest at 31°F and 16°F. A freezing night is all but certain in every month from November to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 20% of years.

Warmth for growing adds up to 3,357 growing degree days a year (base 50°F), fewer than at 58% of the 158 Illinois stations. 35% of them (1,172) have built up by the end of June, and July adds the most, 773. Precipitation totals 38.7 inches a year, most in July (4.9") and least in February (1.8"); May to September bring 56% of it.

The nearest other station, Channahon Dresden Isl Dam, IL, 7 miles east of Morris, has a last frost 4 days earlier (April 16), a first frost 3 days later (October 26), a season 7 days longer.

The first measurable snow (0.1 inch or more) in Morris usually arrives around December 3, and the last of the season around March 23. Those are the middle dates across the winters of 1991–2020 at Morris 1 NW, IL, 1.4 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 28 days after the last snow.

ZIP 60450 is 1 mile from Morris 1 NW, IL, which stands at 524 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 60450 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.