Frost Dates for 49093 — Three Rivers, Michigan

Half of springs at Three Rivers, MI see their last 32°F night by April 30; only one in ten is past it by April 16, and one in ten still has one after May 15. Planting tender crops after May 6 leaves a 30% risk of a frost on them, after May 9 20%, and after May 15 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 17 in half of years, as early as October 1 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 14 days later, around October 31; in spring the one-in-ten date for 28°F is May 5, 10 days before the 32°F one. The freeze-free season lasts 170 days in a typical year, longer than at 76% of the 172 Michigan stations; it reaches 189 days one year in ten and falls short of 148 one year in ten. On average 145 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 10 days longer, to about May 10, and return around October 5. Severe cold of 16°F or below comes every winter, usually between December 4 and March 17.

July is the warmest month at Three Rivers, MI, averaging 82°F by day and 61°F at night; January is the coldest at 31°F and 17°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 47% of years.

Warmth for growing adds up to 2,716 growing degree days a year (base 50°F), more than at 76% of the 172 Michigan stations. 34% of them (923) have built up by the end of June, and July adds the most, 663. Precipitation totals 39.9 inches a year, most in May (4.4") and least in February (2.1"); May to September bring 50% of it.

The nearest other station, Kalamazoo Battle Ck International Airport, MI, 20 miles north of Three Rivers, has a last frost 2 days earlier (April 28), a first frost 1 day later (October 18), a season 2 days longer.

The first measurable snow (0.1 inch or more) in Three Rivers usually arrives around November 23, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at Three Rivers, MI, 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 35 days after the last snow.

ZIP 49093 is 2 miles from Three Rivers, MI, which stands at 810 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 7 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 49093 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.