Port Huron, MI 48059 Frost Dates
Frost dates for Port Huron, MI, ZIP 48059
Around 04/19 is the usual last spring frost, about 234 days away. The first fall frost typically arrives around 11/03, about 196 frost-free days later.
The USDA Plant Hardiness Zone Map puts Port Huron 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 Huron has about 10 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.
How much risk comes with planting early here
04/19 is the middle of 30 years of NOAA records, not a promise. Plant by 04/07 and you're betting against frost in roughly 9 years out of 10. 05/04 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Port Huron compares
Port Huron's growing season runs about 196 days, ranking 18,915 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 5 of 1,153.
Learn more
zone vs. frost date explains why Zone 6a and Port Huron's frost date answer different questions, and the frost range explains how to read the range around Port Huron's dates instead of trusting one.