River Rouge, MI 48218 Frost Dates
Frost dates for River Rouge, MI, ZIP 48218
Around 04/27 is the usual last spring frost, about 242 days away. The first fall frost typically arrives around 10/25, about 181 frost-free days later.
The USDA Plant Hardiness Zone Map puts River Rouge in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 6b around River Rouge 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 River Rouge compares
River Rouge's growing season runs about 181 days, ranking 24,497 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 82 of 1,153.
Learn more
local microclimates explains what one yard in River Rouge can differ from the 48218 normal, and zone vs. frost date explains why Zone 6b and River Rouge's frost date answer different questions.