Frost Dates for 48357 — Highland, Michigan

Half of springs at Milford Gm Proving Ground, MI see their last 32°F night by May 6; only one in ten is past it by April 21, and one in ten still has one after May 22. Planting tender crops after May 13 leaves a 30% risk of a frost on them, after May 17 20%, and after May 22 10%. The 16 days between the even-odds date and the one-in-ten date is narrower than at 38% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 12 in half of years, as early as September 27 one year in ten, and holds off past October 27 one year in ten. A hard freeze of 28°F follows 12 days later, around October 24; in spring the one-in-ten date for 28°F is May 11, 11 days before the 32°F one. The freeze-free season lasts 157 days in a typical year, shorter than at 53% of the 172 Michigan stations; it reaches 177 days one year in ten and falls short of 136 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 12 days longer, to about May 18, and return around October 1. Severe cold of 16°F or below comes every winter, usually between November 26 and March 25.

July is the warmest month at Milford Gm Proving Ground, MI, averaging 82°F by day and 60°F at night; January is the coldest at 31°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 67% of years.

Warmth for growing adds up to 2,617 growing degree days a year (base 50°F), more than at 65% of the 172 Michigan stations. 33% of them (864) have built up by the end of June, and July adds the most, 649.

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

The first measurable snow (0.1 inch or more) in Highland usually arrives around December 1, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Milford Gm Proving Ground, MI, 5.9 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 47 days after the last snow.

ZIP 48357 is 6 miles from Milford Gm Proving Ground, MI, which stands at 970 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 48114 (Brighton). The 2023 USDA Plant Hardiness Zone Map lists ZIP 48357 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.