Harrison, MI 48633 Frost Dates
Frost dates for Harrison, MI, ZIP 48633
Around 05/09 is the usual last spring frost, about 254 days away. The first fall frost typically arrives around 10/04, about 148 frost-free days later.
The USDA Plant Hardiness Zone Map puts Harrison in Zone 5a (-20 to -15°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 5a around Harrison has about 5 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.
The actual range around Harrison's last frost
05/09 is the middle of 30 years of NOAA records, not a promise. Plant by 04/26 and you're betting against frost in roughly 9 years out of 10. 05/23 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Harrison compares
Harrison's growing season runs about 148 days, ranking 35,727 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 841 of 1,153.
Learn more
the frost range explains how to read the range around Harrison's dates instead of trusting one, and local microclimates explains what one yard in Harrison can differ from the 48633 normal.