Monticello, IA 52310 Frost Dates
Monticello, 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 10/10, roughly 164 days after the last spring frost.
Monticello 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 Monticello'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 04/12 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.
Monticello against the rest of the dataset
At roughly 164 frost-free days, Monticello places 30,927 of 40,283 ZIP codes in this dataset. Within IA, it ranks 583 of 1,042.
Learn more
Before leaning on 52310's figures: the frost range explains how to read the range around Monticello's dates instead of trusting one, while local microclimates explains what one yard in Monticello can differ from the 52310 normal.