Southwest City, MO 64863 Frost Dates
64863, near Southwest City, MO: the frost window
Around 04/15 is the usual last spring frost, about 230 days away. Fall's first freeze usually shows up around 10/26, roughly 194 days after the last spring frost.
Zone 7a (0 to 5°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 Southwest City, not a forecast for this year.
Stretching the season past the first frost
Southwest City's growing season runs out in roughly 8 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
04/15 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/31 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/30 and only about 1 year in 10 sees frost after that.
Southwest City against the rest of the dataset
About 194 days separate Southwest City's last and first frost, putting it 19,533 of 40,283 ZIP codes nationally. Within MO, it ranks 644 of 1,129.
Learn more
Two guides worth reading on 64863: zone vs. frost date, on why Zone 7a and Southwest City's frost date answer different questions, and the frost range, on how to read the range around Southwest City's dates instead of trusting one.