Sioux City, IA 51108 Frost Dates
51108, near Sioux City, IA: the frost window
Around 04/29 is the usual last spring frost, about 244 days away. Fall's first freeze usually shows up around 10/05, roughly 159 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Sioux City in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Sioux City's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
04/29 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/16 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/14 and only about 1 year in 10 sees frost after that.
Sioux City against the rest of the dataset
At roughly 159 frost-free days, Sioux City places 32,577 of 40,283 ZIP codes in this dataset. Within IA, it ranks 775 of 1,042.
Learn more
Two guides worth reading on 51108: local microclimates, on what one yard in Sioux City can differ from the 51108 normal, and zone vs. frost date, on why Zone 5a and Sioux City's frost date answer different questions.