Allison, IA 50602 Frost Dates
Allison, IA: when does the frost end?
Typically, the last spring freeze lands around 04/30, roughly 245 days out. Fall's first freeze usually shows up around 10/06, roughly 157 days after the last spring frost.
Allison sits in USDA Zone 5a (-20 to -15°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
With roughly 6 weeks until Allison's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/30 isn't a guarantee
04/30 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 05/14 and only about 1 year in 10 sees frost after that.
Allison against the rest of the dataset
At roughly 157 frost-free days, Allison places 33,387 of 40,283 ZIP codes in this dataset. Within IA, it ranks 842 of 1,042.
Learn more
Before leaning on 50602's figures: the frost range explains how to read the range around Allison's dates instead of trusting one, while local microclimates explains what one yard in Allison can differ from the 50602 normal.