Marion, IA 52499 Frost Dates
52499, near Marion, IA: the frost window
The last spring frost here typically falls around 04/28, about 243 days from today. Fall's first freeze usually shows up around 10/12, roughly 166 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Marion 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
Marion'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.
The actual range around Marion's last frost
04/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/14 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/13 and only about 1 year in 10 sees frost after that.
Marion against the rest of the dataset
Marion's growing season runs about 166 days, ranking 30,292 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 448 of 1,042.
Learn more
Two guides worth reading on 52499: local microclimates, on what one yard in Marion can differ from the 52499 normal, and zone vs. frost date, on why Zone 5a and Marion's frost date answer different questions.