Decatur, IA 50067 Frost Dates
Frost dates for Decatur, IA, ZIP 50067
Around 04/16 is the usual last spring frost, about 231 days away. The first fall frost typically arrives around 10/21, about 186 frost-free days later.
The USDA Plant Hardiness Zone Map puts Decatur in Zone 5b (-15 to -10°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 5b around Decatur 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 04/16 isn't a guarantee
04/16 is the middle of 30 years of NOAA records, not a promise. Plant by 04/02 and you're betting against frost in roughly 9 years out of 10. 05/02 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Decatur compares
About 186 days separate Decatur's last and first frost, putting it 22,959 of 40,283 ZIP codes nationally. Within IA, it ranks 31 of 1,042.
Learn more
local microclimates explains what one yard in Decatur can differ from the 50067 normal, and zone vs. frost date explains why Zone 5b and Decatur's frost date answer different questions.