Frost Dates for 49738 — Grayling, Michigan

Half of springs at Grayling, MI see their last 32°F night by May 23; only one in ten is past it by May 6, and one in ten still has one after June 7. Planting tender crops after May 30 leaves a 30% risk of a frost on them, after June 1 20%, and after June 7 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 September 27 in half of years, as early as September 11 one year in ten, and holds off past October 10 one year in ten. A hard freeze of 28°F follows 12 days later, around October 9; in spring the one-in-ten date for 28°F is May 26, 12 days before the 32°F one. The freeze-free season lasts 124 days in a typical year, shorter than at 93% of the 172 Michigan stations; it reaches 146 days one year in ten and falls short of 104 one year in ten. On average 185 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 June 4, and return around September 14. Severe cold of 16°F or below comes every winter, usually between November 15 and April 6.

July is the warmest month at Grayling, MI, averaging 80°F by day and 55°F at night; January is the coldest at 26°F and 10°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 22% of years.

Warmth for growing adds up to 2,013 growing degree days a year (base 50°F), fewer than at 77% of the 172 Michigan stations. 32% of them (639) have built up by the end of June, and July adds the most, 547. Precipitation totals 33.3 inches a year, most in October (4.0") and least in February (1.4"); May to September bring 49% of it.

The nearest other station, Houghton Lk Roscommon Airport, MI, 23 miles south of Grayling, has a last frost 4 days earlier (May 19), a first frost 4 days earlier (September 23), a season 1 day longer.

The first measurable snow (0.1 inch or more) in Grayling usually arrives around November 4, and the last of the season around April 11. Those are the middle dates across the winters of 1991–2020 at Grayling, MI, 4.2 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 42 days after the last snow.

ZIP 49738 is 4 miles from Grayling, MI, which stands at 1,137 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49738 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.