Frost Dates for 49057 — Hartford, Michigan

Half of springs at Eau Claire 4 NE, MI see their last 32°F night by April 22; only one in ten is past it by April 6, and one in ten still has one after May 7. Planting tender crops after April 28 leaves a 30% risk of a frost on them, after May 1 20%, and after May 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 October 30 in half of years, as early as October 15 one year in ten, and holds off past November 12 one year in ten. A hard freeze of 28°F follows 10 days later, around November 9; in spring the one-in-ten date for 28°F is April 24, 13 days before the 32°F one. The freeze-free season lasts 189 days in a typical year, longer than at 98% of the 172 Michigan stations; it reaches 209 days one year in ten and falls short of 167 one year in ten. On average 122 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 9 days longer, to about May 1, and return around October 17. Severe cold of 16°F or below comes every winter, usually between December 9 and March 11.

July is the warmest month at Eau Claire 4 NE, MI, averaging 85°F by day and 64°F at night; January is the coldest at 33°F and 20°F. A freezing night is all but certain in every month from November 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 22% of years.

Warmth for growing adds up to 3,349 growing degree days a year (base 50°F), the most of the 172 Michigan stations. 35% of them (1,158) have built up by the end of June, and July adds the most, 759. Precipitation totals 38.5 inches a year, most in August (4.5") and least in February (1.9"); May to September bring 49% of it.

The nearest other station, Benton Harbor Airport, MI, 14 miles west of Hartford and 215 feet lower, has a last frost 13 days later (May 5), a first frost 15 days earlier (October 15), a season 28 days shorter.

The first measurable snow (0.1 inch or more) in Hartford usually arrives around November 20, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Eau Claire 4 NE, MI, 13.3 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 17 days after the last snow.

ZIP 49057 is 13 miles from Eau Claire 4 NE, MI, which stands at 840 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 49103 (Berrien Springs). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49057 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.