Frost Dates for 49746 — Hillman, Michigan

Half of springs at Atlanta, MI see their last 32°F night by May 22; only one in ten is past it by May 5, and one in ten still has one after June 5. Planting tender crops after May 28 leaves a 30% risk of a frost on them, after May 31 20%, and after June 5 10%. The 14 days between the even-odds date and the one-in-ten date is narrower than at 80% 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 12 one year in ten, and holds off past October 11 one year in ten. A hard freeze of 28°F follows 14 days later, around October 11; in spring the one-in-ten date for 28°F is May 24, 12 days before the 32°F one. The freeze-free season lasts 127 days in a typical year, shorter than at 88% of the 172 Michigan stations; it reaches 149 days one year in ten and falls short of 106 one year in ten. On average 193 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 3, and return around September 14. Severe cold of 16°F or below comes every winter, usually between November 22 and April 3.

July is the warmest month at Atlanta, 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 19% of years.

Warmth for growing adds up to 1,970 growing degree days a year (base 50°F), fewer than at 82% of the 172 Michigan stations. 30% of them (600) have built up by the end of June, and July adds the most, 545.

The nearest other station, Atlanta 5 WNW, MI, 14 miles west of Hillman and 301 feet higher, has a last frost 11 days earlier (May 11), a first frost 9 days later (October 6), a season 19 days longer.

The first measurable snow (0.1 inch or more) in Hillman usually arrives around November 11, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Atlanta, MI, 9.8 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 39 days after the last snow.

ZIP 49746 is 10 miles from Atlanta, MI, which stands at 879 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 49709 (Atlanta). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49746 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.