Frost Dates for 48462 — Ortonville, Michigan

Half of springs at Goodrich, MI see their last 32°F night by May 1; only one in ten is past it by April 20, and one in ten still has one after May 18. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 13 20%, and after May 18 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 October 14 in half of years, as early as September 30 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 14 days later, around October 28; in spring the one-in-ten date for 28°F is May 6, 12 days before the 32°F one. The freeze-free season lasts 164 days in a typical year, longer than at 65% of the 172 Michigan stations; it reaches 183 days one year in ten and falls short of 143 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 10 days longer, to about May 11, and return around October 2. Severe cold of 16°F or below comes every winter, usually between December 1 and March 22.

July is the warmest month at Goodrich, MI, averaging 82°F by day and 59°F at night; January is the coldest at 30°F and 15°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 52% of years.

Warmth for growing adds up to 2,561 growing degree days a year (base 50°F), more than at 59% of the 172 Michigan stations. 33% of them (833) have built up by the end of June, and July adds the most, 629. Precipitation totals 32.3 inches a year, most in May (3.7") and least in February (1.5"); May to September bring 52% of it.

The nearest other station, White Lake 4E, MI, 10 miles south of Ortonville, has a last frost 9 days later (May 10), a first frost 8 days earlier (October 6), a season 16 days shorter.

The first measurable snow (0.1 inch or more) in Ortonville usually arrives around November 17, and the last of the season around April 15. Those are the middle dates across the winters of 1991–2020 at White Lake 4E, MI, 10.3 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 48462 is 6 miles from Goodrich, MI, which stands at 910 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 48442 (Holly). The 2023 USDA Plant Hardiness Zone Map lists ZIP 48462 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.