Frost Dates for 49090 — South Haven, Michigan

Half of springs at S Haven, MI see their last 32°F night by April 17; only one in ten is past it by April 3, and one in ten still has one after May 4. Planting tender crops after April 23 leaves a 30% risk of a frost on them, after April 29 20%, and after May 4 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 62% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by November 5 in half of years, as early as October 24 one year in ten, and holds off past November 19 one year in ten. A hard freeze of 28°F follows 9 days later, around November 14; in spring the one-in-ten date for 28°F is April 20, 14 days before the 32°F one. The freeze-free season lasts 201 days in a typical year, the longest of the 172 Michigan stations; it reaches 221 days one year in ten and falls short of 179 one year in ten. On average 108 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 13 days longer, to about April 30, and return around October 25. Severe cold of 16°F or below comes every winter, usually between December 20 and March 7.

July is the warmest month at S Haven, MI, averaging 80°F by day and 66°F at night; January is the coldest at 34°F and 22°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 17% of years.

Warmth for growing adds up to 2,980 growing degree days a year (base 50°F), more than at 95% of the 172 Michigan stations. 31% of them (915) have built up by the end of June, and July adds the most, 707.

The nearest other station, Bloomingdale, MI, 15 miles east of South Haven, has a last frost 20 days later (May 7), a first frost 25 days earlier (October 11), a season 45 days shorter.

The first measurable snow (0.1 inch or more) in South Haven usually arrives around November 17, and the last of the season around April 1. Those are the middle dates across the winters of 1991–2020 at Bloomingdale, MI, 14.7 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 16 days after the last snow.

ZIP 49090 is 2 miles from S Haven, MI, which stands at 590 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 49090 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.