Frost Dates for 49031 — Cassopolis, Michigan

Half of springs at Dowagiac 1 W, MI see their last 32°F night by May 4; only one in ten is past it by April 21, and one in ten still has one after May 22. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 16 20%, and after May 22 10%. The 18 days between the even-odds date and the one-in-ten date is wider than at 81% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 11 in half of years, as early as September 27 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 15 days later, around October 26; in spring the one-in-ten date for 28°F is May 10, 12 days before the 32°F one. The freeze-free season lasts 158 days in a typical year, shorter than at 50% of the 172 Michigan stations; it reaches 180 days one year in ten and falls short of 135 one year in ten. On average 145 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 May 15, and return around September 30. Severe cold of 16°F or below comes every winter, usually between December 2 and March 22.

July is the warmest month at Dowagiac 1 W, MI, averaging 82°F by day and 60°F at night; January is the coldest at 31°F and 16°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 62% of years.

Warmth for growing adds up to 2,634 growing degree days a year (base 50°F), more than at 65% of the 172 Michigan stations. 34% of them (895) have built up by the end of June, and July adds the most, 643. Precipitation totals 41.7 inches a year, most in June (4.3") and least in February (2.4"); May to September bring 48% of it.

The nearest other station, Niles, MI, 15 miles west of Cassopolis, has a last frost 7 days earlier (April 27), a first frost 14 days later (October 25), a season 22 days longer.

The first measurable snow (0.1 inch or more) in Cassopolis usually arrives around November 23, and the last of the season around March 24. Those are the middle dates across the winters of 1991–2020 at Dowagiac 1 W, MI, 9.1 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 41 days after the last snow.

ZIP 49031 is 9 miles from Dowagiac 1 W, MI, which stands at 740 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 49047 (Dowagiac). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49031 in zone 6a, the band where the coldest night of the year averaged -10 to -5°F (-23.3 to -20.6°C) over 1991–2020; a zone describes winter lows, not frost dates.