Frost Dates for 48740 — Harrisville, Michigan

Half of springs at Harrisville 2NNE, MI see their last 32°F night by May 8; only one in ten is past it by April 26, and one in ten still has one after May 24. Planting tender crops after May 15 leaves a 30% risk of a frost on them, after May 19 20%, and after May 24 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 16 in half of years, as early as October 2 one year in ten, and holds off past October 30 one year in ten. A hard freeze of 28°F follows 13 days later, around October 29; in spring the one-in-ten date for 28°F is May 12, 12 days before the 32°F one. The freeze-free season lasts 160 days in a typical year, longer than at 51% of the 172 Michigan stations; it reaches 178 days one year in ten and falls short of 140 one year in ten. On average 150 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 21, and return around October 4. Severe cold of 16°F or below comes every winter, usually between December 1 and March 26.

July is the warmest month at Harrisville 2NNE, MI, averaging 74°F by day and 58°F at night; January is the coldest at 26°F and 14°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to September the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 75% of years.

Warmth for growing adds up to 1,682 growing degree days a year (base 50°F), fewer than at 94% of the 172 Michigan stations. 23% of them (388) have built up by the end of June, and July adds the most, 484. Precipitation totals 29.2 inches a year, most in July (3.4") and least in February (1.1"); May to September bring 54% of it.

The nearest other station, E Tawas, MI, 27 miles south of Harrisville, has the same 50% last-frost date, a first frost 11 days earlier (October 5), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Harrisville usually arrives around November 19, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Harrisville 2NNE, MI, 3.7 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 24 days after the last snow.

ZIP 48740 is 4 miles from Harrisville 2NNE, MI, which stands at 585 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 48740 in zone 5b, the band where the coldest night of the year averaged -15 to -10°F (-26.1 to -23.3°C) over 1991–2020; a zone describes winter lows, not frost dates.