Port Sanilac, MI 48469 Frost Dates
Frost dates for Port Sanilac, MI, ZIP 48469
Typically, the last spring freeze lands around 05/04, roughly 249 days out. The first fall frost typically arrives around 10/24, about 171 frost-free days later.
The USDA Plant Hardiness Zone Map puts Port Sanilac in Zone 6a (-10 to -5°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 6a around Port Sanilac 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 05/04 isn't a guarantee
05/04 is the middle of 30 years of NOAA records, not a promise. Plant by 04/20 and you're betting against frost in roughly 9 years out of 10. 05/20 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Port Sanilac compares
At roughly 171 frost-free days, Port Sanilac places 28,774 of 40,283 ZIP codes in this dataset. Within MI, it ranks 301 of 1,153.
Learn more
the frost range explains how to read the range around Port Sanilac's dates instead of trusting one, and local microclimates explains what one yard in Port Sanilac can differ from the 48469 normal.