Andover, IA 52771 Frost Dates
52771, near Andover, IA: the frost window
Typically, the last spring freeze lands around 05/02, roughly 247 days out. Fall's first freeze usually shows up around 10/07, roughly 154 days after the last spring frost.
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 Andover, not a forecast for this year.
Stretching the season past the first frost
Andover's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/18 and only about 1 year in 10 sees frost after that.
Andover against the rest of the dataset
About 154 days separate Andover's last and first frost, putting it 34,472 of 40,283 ZIP codes nationally. Within IA, it ranks 914 of 1,042.
Learn more
Two guides worth reading on 52771: local microclimates, on what one yard in Andover can differ from the 52771 normal, and zone vs. frost date, on why Zone 5a and Andover's frost date answer different questions.