Grundy Center, IA 50638 Frost Dates
50638, near Grundy Center, IA: the frost window
The last spring frost here typically falls around 04/29, about 244 days from today. Fall's first freeze usually shows up around 10/09, roughly 160 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 Grundy Center, not a forecast for this year.
Stretching the season past the first frost
Grundy Center'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.
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 04/15 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Grundy Center against the rest of the dataset
At roughly 160 frost-free days, Grundy Center places 32,369 of 40,283 ZIP codes in this dataset. Within IA, it ranks 757 of 1,042.
Learn more
Two guides worth reading on 50638: local microclimates, on what one yard in Grundy Center can differ from the 50638 normal, and zone vs. frost date, on why Zone 5a and Grundy Center's frost date answer different questions.