Frost Dates for 52761 — Muscatine, Iowa

Half of springs at Illinois City Dam 16, IL see their last 32°F night by April 18; only one in ten is past it by April 5, and one in ten still has one after May 2. Planting tender crops after April 24 leaves a 30% risk of a frost on them, after April 28 20%, and after May 2 10%. The 14 days between the even-odds date and the one-in-ten date is wider than at 58% of the 132 Iowa 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 8 days later, around November 1; in spring the one-in-ten date for 28°F is April 25, 7 days before the 32°F one. The freeze-free season lasts 188 days in a typical year, longer than at 95% of the 132 Iowa stations; it reaches 207 days one year in ten and falls short of 168 one year in ten. On average 131 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 11 days longer, to about April 29, and return around October 15. Severe cold of 16°F or below comes every winter, usually between November 30 and March 8.

July is the warmest month at Illinois City Dam 16, IL, averaging 85°F by day and 65°F at night; January is the coldest at 31°F and 13°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 14% of years.

Warmth for growing adds up to 3,309 growing degree days a year (base 50°F), more than at 86% of the 132 Iowa stations. 35% of them (1,156) have built up by the end of June, and July adds the most, 770. Precipitation totals 36.5 inches a year, most in June (5.0") and least in January (1.2"); May to September bring 58% of it.

The nearest other station, Muscatine 2N, IA, 5 miles northwest of Muscatine, has the same 50% last-frost date, a first frost 2 days earlier (October 22), a season 4 days shorter.

The first measurable snow (0.1 inch or more) in Muscatine usually arrives around December 7, and the last of the season around March 4. Those are the middle dates across the winters of 1991–2020 at Illinois City Dam 16, IL, 0.9 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 45 days after the last snow.

ZIP 52761 is under a mile from Illinois City Dam 16, IL, which stands at 550 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 52761 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.