St. Charles, MO 63301 Frost Dates
St. Charles, MO: when does the frost end?
Typically, the last spring freeze lands around 04/08, roughly 223 days out. Fall's first freeze usually shows up around 10/29, roughly 203 days after the last spring frost.
Zone 6b (-5 to 0°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 St. Charles, not a forecast for this year.
Stretching the season past the first frost
With roughly 9 weeks until St. Charles's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/08 isn't a guarantee
04/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/24 and only about 1 year in 10 sees frost after that.
St. Charles against the rest of the dataset
About 203 days separate St. Charles's last and first frost, putting it 16,834 of 40,283 ZIP codes nationally. Within MO, it ranks 323 of 1,129.
Learn more
Before leaning on 63301's figures: the frost range explains how to read the range around St. Charles's dates instead of trusting one, while local microclimates explains what one yard in St. Charles can differ from the 63301 normal.