Frost Dates for 48708 — Bay City, Michigan

Half of springs at Essexville, MI see their last 32°F night by April 27; only one in ten is past it by April 15, and one in ten still has one after May 11. Planting tender crops after May 2 leaves a 30% risk of a frost on them, after May 5 20%, and after May 11 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 October 20 in half of years, as early as October 5 one year in ten, and holds off past November 2 one year in ten. A hard freeze of 28°F follows 12 days later, around November 1; in spring the one-in-ten date for 28°F is April 30, 11 days before the 32°F one. The freeze-free season lasts 173 days in a typical year, longer than at 82% of the 172 Michigan stations; it reaches 192 days one year in ten and falls short of 153 one year in ten. On average 139 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 6, and return around October 7. Severe cold of 16°F or below comes every winter, usually between December 4 and March 19.

July is the warmest month at Essexville, MI, averaging 82°F by day and 62°F at night; January is the coldest at 30°F and 16°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 35% of years.

Warmth for growing adds up to 2,675 growing degree days a year (base 50°F), more than at 69% of the 172 Michigan stations. 33% of them (871) have built up by the end of June, and July adds the most, 679. Precipitation totals 33.3 inches a year, most in August (3.8") and least in January (1.7"); May to September bring 51% of it.

The nearest other station, Auburn 2NE, MI, 8 miles northwest of Bay City, has a last frost 6 days later (May 3), a first frost 6 days earlier (October 14), a season 12 days shorter.

The first measurable snow (0.1 inch or more) in Bay City usually arrives around November 25, and the last of the season around March 19. Those are the middle dates across the winters of 1991–2020 at Essexville, MI, 2.8 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 48708 is 3 miles from Essexville, MI, which stands at 588 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 48706 (Bay City). The 2023 USDA Plant Hardiness Zone Map lists ZIP 48708 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.