Mattoon, WI 54450 Frost Dates
Frost dates for Mattoon, WI, ZIP 54450
Around 05/14 is the usual last spring frost, about 259 days away. The first fall frost typically arrives around 09/30, about 139 frost-free days later.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Mattoon, not a forecast for this year.
What to do before the first frost
Zone 4b around Mattoon 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.
Why 05/14 isn't a guarantee
05/14 is the middle of 30 years of NOAA records, not a promise. Plant by 04/30 and you're betting against frost in roughly 9 years out of 10. 05/28 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mattoon compares
About 139 days separate Mattoon's last and first frost, putting it 37,270 of 40,283 ZIP codes nationally. Within WI, it ranks 736 of 860.
Learn more
local microclimates explains what one yard in Mattoon can differ from the 54450 normal, and zone vs. frost date explains why Zone 4b and Mattoon's frost date answer different questions.