Sigourney, IA 52591 Frost Dates
52591, near Sigourney, IA: the frost window
The last spring frost here typically falls around 04/23, about 238 days from today. Fall's first freeze usually shows up around 10/14, roughly 172 days after the last spring frost.
Zone 5b (-15 to -10°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 Sigourney, not a forecast for this year.
Stretching the season past the first frost
Sigourney's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/23 isn't a guarantee
04/23 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/07 and only about 1 year in 10 sees frost after that.
Sigourney against the rest of the dataset
Sigourney's growing season runs about 172 days, ranking 28,347 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 267 of 1,042.
Learn more
Two guides worth reading on 52591: the frost range, on how to read the range around Sigourney's dates instead of trusting one, and local microclimates, on what one yard in Sigourney can differ from the 52591 normal.