Des Moines, IA 50309 Frost Dates
50309, near Des Moines, IA: the frost window
The last spring frost here typically falls around 04/18, about 233 days from today. Fall's first freeze usually shows up around 10/20, roughly 184 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Des Moines in Zone 5b (-15 to -10°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
Des Moines's growing season runs out in roughly 8 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
04/18 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/04 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/02 and only about 1 year in 10 sees frost after that.
Des Moines against the rest of the dataset
About 184 days separate Des Moines's last and first frost, putting it 23,378 of 40,283 ZIP codes nationally. Within IA, it ranks 46 of 1,042.
Learn more
Two guides worth reading on 50309: local microclimates, on what one yard in Des Moines can differ from the 50309 normal, and zone vs. frost date, on why Zone 5b and Des Moines's frost date answer different questions.