Frost Dates for 49085 — Saint Joseph, Michigan

Half of springs at Benton Harbor Airport, MI see their last 32°F night by May 5; only one in ten is past it by April 20, and one in ten still has one after May 26. Planting tender crops after May 14 leaves a 30% risk of a frost on them, after May 19 20%, and after May 26 10%. The 21 days between the even-odds date and the one-in-ten date is wider than at 97% of the 172 Michigan stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by October 15 in half of years, as early as September 28 one year in ten, and holds off past November 1 one year in ten. A hard freeze of 28°F follows 15 days later, around October 30; in spring the one-in-ten date for 28°F is May 11, 15 days before the 32°F one. The freeze-free season lasts 161 days in a typical year, longer than at 56% of the 172 Michigan stations; it reaches 184 days one year in ten and falls short of 136 one year in ten. On average 128 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 16 days longer, to about May 21, and return around October 3. Severe cold of 16°F or below comes every winter, usually between December 6 and March 20.

July is the warmest month at Benton Harbor Airport, MI, averaging 83°F by day and 62°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 August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 64% of years.

Warmth for growing adds up to 2,955 growing degree days a year (base 50°F), more than at 94% of the 172 Michigan stations. 33% of them (962) have built up by the end of June, and July adds the most, 701. Precipitation totals 38.3 inches a year, most in October (4.4") and least in February (1.9"); May to September bring 47% of it.

The nearest other station, Eau Claire 4 NE, MI, 13 miles east of Saint Joseph and 215 feet higher, has a last frost 13 days earlier (April 22), a first frost 15 days later (October 30), a season 28 days longer.

The first measurable snow (0.1 inch or more) in Saint Joseph usually arrives around November 23, and the last of the season around March 20. Those are the middle dates across the winters of 1991–2020 at Benton Harbor Airport, MI, 4.4 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 46 days after the last snow.

ZIP 49085 is 4 miles from Benton Harbor Airport, MI, which stands at 625 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 6 other ZIP codes share the station; its figures are presented in full for 49022 (Benton Harbor). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49085 in zone 6b, the band where the coldest night of the year averaged -5 to 0°F (-20.6 to -17.8°C) over 1991–2020; a zone describes winter lows, not frost dates.