St. Joseph, MO 64503 Frost Dates
64503, near St. Joseph, MO: the frost window
The last spring frost here typically falls around 04/19, about 234 days from today. Fall's first freeze usually shows up around 10/17, roughly 180 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts St. Joseph in Zone 6a (-10 to -5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
St. Joseph's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/19 isn't a guarantee
04/19 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/05 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/03 and only about 1 year in 10 sees frost after that.
St. Joseph against the rest of the dataset
At roughly 180 frost-free days, St. Joseph places 24,766 of 40,283 ZIP codes in this dataset. Within MO, it ranks 1,008 of 1,129.
Learn more
Two guides worth reading on 64503: local microclimates, on what one yard in St. Joseph can differ from the 64503 normal, and zone vs. frost date, on why Zone 6a and St. Joseph's frost date answer different questions.