Frost Dates for 49887 — Stephenson, Michigan

Half of springs at Stephenson 5WSW, MI see their last 32°F night by May 22; only one in ten is past it by May 7, and one in ten still has one after June 4. Planting tender crops after May 28 leaves a 30% risk of a frost on them, after May 31 20%, and after June 4 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 95% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by September 27 in half of years, as early as September 10 one year in ten, and holds off past October 10 one year in ten. A hard freeze of 28°F follows 10 days later, around October 7; in spring the one-in-ten date for 28°F is May 25, 10 days before the 32°F one. The freeze-free season lasts 126 days in a typical year, shorter than at 91% of the 172 Michigan stations; it reaches 146 days one year in ten and falls short of 106 one year in ten. On average 191 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 12 days longer, to about June 3, and return around September 13. Severe cold of 16°F or below comes every winter, usually between November 16 and April 5.

July is the warmest month at Stephenson 5WSW, MI, averaging 81°F by day and 54°F at night; January is the coldest at 27°F and 5°F. A freezing night is all but certain in every month from October to May (a 90% chance or more). From July to August the chance of a 32°F night stays under 10% each month. In spring, June still brings one in 16% of years.

Warmth for growing adds up to 1,972 growing degree days a year (base 50°F), fewer than at 80% of the 172 Michigan stations. 31% of them (602) have built up by the end of June, and July adds the most, 546.

The nearest other station, Marinette, WI, 22 miles south of Stephenson, has a last frost 18 days earlier (May 4), a first frost 14 days later (October 11), a season 34 days longer.

The first measurable snow (0.1 inch or more) in Stephenson usually arrives around November 14, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Stephenson 5WSW, MI, 4.1 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 40 days after the last snow.

ZIP 49887 is 4 miles from Stephenson 5WSW, MI, which stands at 690 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 1 other ZIP code shares the station; its figures are presented in full for 54177 (Wausaukee). The 2023 USDA Plant Hardiness Zone Map lists ZIP 49887 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.