Sioux City, IA 51101 Frost Dates
Frost dates for Sioux City, IA, ZIP 51101
Typically, the last spring freeze lands around 04/29, roughly 244 days out. 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.
How much risk comes with planting early here
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
At roughly 159 frost-free days, Sioux City places 32,572 of 40,283 ZIP codes in this dataset. Within IA, it ranks 770 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.