Detroit, MI 48238 Frost Dates
Frost dates for Detroit, MI, ZIP 48238
The last spring frost here typically falls around 04/27, about 242 days from today. The first fall frost typically arrives around 10/25, about 181 frost-free days later.
Zone 6b (-5 to 0°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Detroit, not a forecast for this year.
What to do before the first frost
Zone 6b around Detroit has about 8 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 04/27 isn't a guarantee
04/27 is the middle of 30 years of NOAA records, not a promise. Plant by 04/12 and you're betting against frost in roughly 9 years out of 10. 05/11 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Detroit compares
Detroit's growing season runs about 181 days, ranking 24,372 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 72 of 1,153.
Learn more
local microclimates explains what one yard in Detroit can differ from the 48238 normal, and zone vs. frost date explains why Zone 6b and Detroit's frost date answer different questions.