Frost Dates for 49449 — Pentwater, Michigan

Half of springs at Ludington 4 SE, MI see their last 32°F night by May 17; only one in ten is past it by April 28, and one in ten still has one after June 1. Planting tender crops after May 23 leaves a 30% risk of a frost on them, after May 27 20%, and after June 1 10%. The 15 days between the even-odds date and the one-in-ten date is narrower than at 55% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 7 in half of years, as early as September 20 one year in ten, and holds off past October 25 one year in ten. A hard freeze of 28°F follows 14 days later, around October 21; in spring the one-in-ten date for 28°F is May 21, 11 days before the 32°F one. The freeze-free season lasts 144 days in a typical year, shorter than at 72% of the 172 Michigan stations; it reaches 168 days one year in ten and falls short of 120 one year in ten. On average 149 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 May 30, and return around September 26. Severe cold of 16°F or below comes every winter, usually between December 2 and March 26.

July is the warmest month at Ludington 4 SE, MI, averaging 79°F by day and 58°F at night; January is the coldest at 29°F and 17°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 82% of years and June still brings one in 11% of years.

Warmth for growing adds up to 2,166 growing degree days a year (base 50°F), fewer than at 67% of the 172 Michigan stations. 31% of them (667) have built up by the end of June, and July adds the most, 566.

The nearest other station, Hart 3 WSW, MI, 8 miles south of Pentwater, has a last frost 5 days earlier (May 12), a first frost 3 days later (October 10), a season 7 days longer.

The first measurable snow (0.1 inch or more) in Pentwater usually arrives around November 17, and the last of the season around April 10. Those are the middle dates across the winters of 1991–2020 at Ludington 4 SE, MI, 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 37 days after the last snow.

ZIP 49449 is 8 miles from Ludington 4 SE, MI, which stands at 690 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 49431 (Ludington). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49449 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.