Frost Dates for 55972 — Saint Charles, Minnesota

Half of springs at Minnesota City Dam 5, MN see their last 32°F night by April 23; only one in ten is past it by April 9, and one in ten still has one after May 6. Planting tender crops after April 29 leaves a 30% risk of a frost on them, after May 2 20%, and after May 6 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 61% of the 142 Minnesota stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 16 in half of years, as early as October 2 one year in ten, and holds off past October 29 one year in ten. A hard freeze of 28°F follows 9 days later, around October 25; in spring the one-in-ten date for 28°F is April 27, 9 days before the 32°F one. The freeze-free season lasts 175 days in a typical year, longer than at 95% of the 142 Minnesota stations; it reaches 193 days one year in ten and falls short of 155 one year in ten. On average 140 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 3, and return around October 5. Severe cold of 16°F or below comes every winter, usually between November 20 and March 20.

July is the warmest month at Minnesota City Dam 5, MN, averaging 83°F by day and 64°F at night; January is the coldest at 23°F and 8°F. A freezing night is all but certain in every month from October 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 25% of years.

Warmth for growing adds up to 2,823 growing degree days a year (base 50°F), more than at 92% of the 142 Minnesota stations. 34% of them (960) have built up by the end of June, and July adds the most, 724. Precipitation totals 35.4 inches a year, most in June (5.1") and least in January (1.1"); May to September bring 62% of it.

The nearest other station, Rushford, MN, 20 miles southeast of Saint Charles, has a last frost 15 days later (May 8), a first frost 13 days earlier (October 3), a season 28 days shorter.

The first measurable snow (0.1 inch or more) in Saint Charles usually arrives around November 16, and the last of the season around April 10. Those are the middle dates across the winters of 1991–2020 at Altura 5W, MN, 6 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 13 days after the last snow.

ZIP 55972 is 18 miles from Minnesota City Dam 5, MN, which stands at 670 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 55972 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.