Marion, IA 52408 Frost Dates
Marion, IA: when does the frost end?
Around 04/28 is the usual last spring frost, about 243 days away. 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
With roughly 6 weeks until Marion's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
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 30,287 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 443 of 1,042.
Learn more
Before leaning on 52408's figures: local microclimates explains what one yard in Marion can differ from the 52408 normal, while zone vs. frost date explains why Zone 5a and Marion's frost date answer different questions.