South Lyon, MI 48178 Frost Dates
Frost dates for South Lyon, MI, ZIP 48178
Typically, the last spring freeze lands around 05/05, roughly 250 days out. The first fall frost typically arrives around 10/13, about 160 frost-free days later.
South Lyon sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 6a around South Lyon has about 7 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 05/05 isn't a guarantee
05/05 is the middle of 30 years of NOAA records, not a promise. Plant by 04/22 and you're betting against frost in roughly 9 years out of 10. 05/21 is the safer bet, historically only a 1-in-10 chance of frost that late.
How South Lyon compares
About 160 days separate South Lyon's last and first frost, putting it 32,263 of 40,283 ZIP codes nationally. Within MI, it ranks 615 of 1,153.
Learn more
local microclimates explains what one yard in South Lyon can differ from the 48178 normal, and zone vs. frost date explains why Zone 6a and South Lyon's frost date answer different questions.