Frost Dates for 48879 — Saint Johns, Michigan

Half of springs at Saint Johns, MI see their last 32°F night by April 28; only one in ten is past it by April 12, and one in ten still has one after May 12. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 7 20%, and after May 12 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 24 in half of years, as early as October 7 one year in ten, and holds off past November 7 one year in ten. A hard freeze of 28°F follows 12 days later, around November 5; in spring the one-in-ten date for 28°F is April 30, 12 days before the 32°F one. The freeze-free season lasts 179 days in a typical year, longer than at 94% of the 172 Michigan stations; it reaches 199 days one year in ten and falls short of 158 one year in ten. On average 144 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 7, and return around October 11. Severe cold of 16°F or below comes every winter, usually between December 7 and March 16.

July is the warmest month at Saint Johns, MI, averaging 83°F by day and 62°F at night; January is the coldest at 31°F and 18°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 39% of years.

Warmth for growing adds up to 2,891 growing degree days a year (base 50°F), more than at 90% of the 172 Michigan stations. 33% of them (946) have built up by the end of June, and July adds the most, 705. Precipitation totals 34.1 inches a year, most in May (3.8") and least in February (1.8"); May to September bring 49% of it.

The nearest other station, Lansing Capital City Airport, MI, 15 miles south of Saint Johns, has a last frost 3 days later (May 1), a first frost 11 days earlier (October 13), a season 17 days shorter.

The first measurable snow (0.1 inch or more) in Saint Johns usually arrives around November 25, and the last of the season around April 5. Those are the middle dates across the winters of 1991–2020 at Saint Johns, MI, 1.4 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 23 days after the last snow.

ZIP 48879 is 1 mile from Saint Johns, MI, which stands at 743 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 5 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 48879 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.