Sioux City, IA 51105 Frost Dates
Frost dates for Sioux City, IA, ZIP 51105
The last spring frost here typically falls around 04/29, about 244 days from today. The first fall frost typically arrives around 10/05, about 159 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 Sioux City, not a forecast for this year.
What to do before the first frost
Zone 5a around Sioux City 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 04/29 isn't a guarantee
04/29 is the middle of 30 years of NOAA records, not a promise. Plant by 04/16 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 Sioux City compares
About 159 days separate Sioux City's last and first frost, putting it 32,575 of 40,283 ZIP codes nationally. Within IA, it ranks 773 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Sioux City's frost date answer different questions, and the frost range explains how to read the range around Sioux City's dates instead of trusting one.