Ionia, IA 50645 Frost Dates
Frost dates for Ionia, IA, ZIP 50645
Typically, the last spring freeze lands around 05/02, roughly 247 days out. The first fall frost typically arrives around 10/05, about 155 frost-free days later.
Zone 5a (-20 to -15°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 Ionia, not a forecast for this year.
What to do before the first frost
Zone 5a around Ionia 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 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/17 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ionia compares
At roughly 155 frost-free days, Ionia places 34,152 of 40,283 ZIP codes in this dataset. Within IA, it ranks 884 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Ionia's frost date answer different questions, and the frost range explains how to read the range around Ionia's dates instead of trusting one.