Marshalltown, IA 50158 Frost Dates
Marshalltown, 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 10/07, roughly 162 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Marshalltown 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 Marshalltown's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/28 isn't a guarantee
04/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/11 and only about 1 year in 10 sees frost after that.
Marshalltown against the rest of the dataset
At roughly 162 frost-free days, Marshalltown places 31,643 of 40,283 ZIP codes in this dataset. Within IA, it ranks 688 of 1,042.
Learn more
Before leaning on 50158's figures: local microclimates explains what one yard in Marshalltown can differ from the 50158 normal, while zone vs. frost date explains why Zone 5a and Marshalltown's frost date answer different questions.