Frost Dates for 48239 — Redford, Michigan

Half of springs at Dearborn, MI see their last 32°F night by May 1; only one in ten is past it by April 17, and one in ten still has one after May 18. Planting tender crops after May 8 leaves a 30% risk of a frost on them, after May 12 20%, and after May 18 10%. The 17 days between the even-odds date and the one-in-ten date is wider than at 62% of the 172 Michigan stations behind this site's ZIP pages.

In fall the first 32°F night comes by October 15 in half of years, as early as October 1 one year in ten, and holds off past October 28 one year in ten. A hard freeze of 28°F follows 13 days later, around October 28; in spring the one-in-ten date for 28°F is May 7, 11 days before the 32°F one. The freeze-free season lasts 166 days in a typical year, longer than at 72% of the 172 Michigan stations; it reaches 186 days one year in ten and falls short of 147 one year in ten. On average 136 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 11 days longer, to about May 12, and return around October 5. Severe cold of 16°F or below comes every winter, usually between December 4 and March 16.

July is the warmest month at Dearborn, MI, averaging 84°F by day and 62°F at night; January is the coldest at 32°F and 18°F. A freezing night is all but certain in every month from October 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 53% of years.

Warmth for growing adds up to 2,901 growing degree days a year (base 50°F), more than at 92% of the 172 Michigan stations. 32% of them (941) have built up by the end of June, and July adds the most, 707. Precipitation totals 35.1 inches a year, most in May (3.6") and least in February (2.3"); May to September bring 47% of it.

The nearest other station, Dearborn #2, MI, 6 miles east of Redford, has a last frost 4 days earlier (April 27), a first frost 10 days later (October 25), a season 15 days longer.

The first measurable snow (0.1 inch or more) in Redford usually arrives around December 4, and the last of the season around March 26. Those are the middle dates across the winters of 1991–2020 at Dearborn, MI, 5 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 36 days after the last snow.

ZIP 48239 is 5 miles from Dearborn, MI, which stands at 605 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 10 other ZIP codes share the station; its figures are presented in full for 48185 (Westland). The 2023 USDA Plant Hardiness Zone Map lists ZIP 48239 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.