Frost Dates for 49441 — Muskegon, Michigan

Half of springs at Muskegon Co Airport, MI see their last 32°F night by April 30; only one in ten is past it by April 17, and one in ten still has one after May 18. Planting tender crops after May 7 leaves a 30% risk of a frost on them, after May 12 20%, and after May 18 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 19 in half of years, as early as October 2 one year in ten, and holds off past November 3 one year in ten. A hard freeze of 28°F follows 14 days later, around November 2; in spring the one-in-ten date for 28°F is May 7, 11 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, longer than at 76% of the 172 Michigan stations; it reaches 192 days one year in ten and falls short of 147 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 12 days longer, to about May 12, and return around October 6. Severe cold of 16°F or below comes every winter, usually between December 17 and March 15.

July is the warmest month at Muskegon Co Airport, MI, averaging 82°F by day and 62°F at night; January is the coldest at 33°F and 21°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 49% of years.

Warmth for growing adds up to 2,760 growing degree days a year (base 50°F), more than at 81% of the 172 Michigan stations. 32% of them (875) have built up by the end of June, and July adds the most, 679. Precipitation totals 35.2 inches a year, most in October (3.8") and least in February (2.1"); May to September bring 45% of it.

The nearest other station, Grand Haven Wwtp, MI, 10 miles south of Muskegon, has the same 50% last-frost date, a first frost 5 days later (October 24), a season 5 days longer.

The first measurable snow (0.1 inch or more) in Muskegon usually arrives around November 16, and the last of the season around April 7. Those are the middle dates across the winters of 1991–2020 at Muskegon Co Airport, MI, 2.5 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 23 days after the last snow.

ZIP 49441 is 3 miles from Muskegon Co Airport, MI, which stands at 625 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 4 other ZIP codes share the station; its figures are presented in full for 49442 (Muskegon). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49441 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.