Frost Dates for 52641 — Mt Pleasant, Iowa

Half of springs at Mt Pleasant 1 SSW, IA see their last 32°F night by April 30; only one in ten is past it by April 13, and one in ten still has one after May 14. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 9 20%, and after May 14 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 10 in half of years, as early as September 24 one year in ten, and holds off past October 23 one year in ten. A hard freeze of 28°F follows 10 days later, around October 20; in spring the one-in-ten date for 28°F is May 5, 9 days before the 32°F one. The freeze-free season lasts 163 days in a typical year, shorter than at 58% of the 132 Iowa stations; it reaches 183 days one year in ten and falls short of 142 one year in ten. On average 130 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 9 days longer, to about May 9, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 18 and March 17.

July is the warmest month at Mt Pleasant 1 SSW, IA, averaging 85°F by day and 62°F at night; January is the coldest at 31°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 48% of years.

Warmth for growing adds up to 3,118 growing degree days a year (base 50°F), more than at 63% of the 132 Iowa stations. 35% of them (1,082) have built up by the end of June, and July adds the most, 728. Precipitation totals 38.6 inches a year, most in May (5.1") and least in January (1.4"); May to September bring 59% of it.

The nearest other station, Fairfield, IA, 20 miles west of Mt Pleasant, has a last frost 3 days earlier (April 27), a first frost 2 days later (October 12), a season 5 days longer.

The first measurable snow (0.1 inch or more) in Mt Pleasant usually arrives around December 4, and the last of the season around March 21. Those are the middle dates across the winters of 1991–2020 at Mt Pleasant 1 SSW, IA, 1.8 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 40 days after the last snow.

ZIP 52641 is 2 miles from Mt Pleasant 1 SSW, IA, which stands at 730 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 52641 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.