Savanna, IL 61074 Frost Dates
Savanna, IL: when does the frost end?
Around 05/02 is the usual last spring frost, about 247 days away. Fall's first freeze usually shows up around 10/07, roughly 154 days after the last spring frost.
Zone 5a (-20 to -15°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Savanna, not a forecast for this year.
Stretching the season past the first frost
With roughly 6 weeks until Savanna's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/18 and only about 1 year in 10 sees frost after that.
Savanna against the rest of the dataset
At roughly 154 frost-free days, Savanna places 34,331 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,543 of 1,548.
Learn more
Before leaning on 61074's figures: the frost range explains how to read the range around Savanna's dates instead of trusting one, while local microclimates explains what one yard in Savanna can differ from the 61074 normal.