St. Mary, MO 63673 Frost Dates
Frost dates for St. Mary, MO, ZIP 63673
The last spring frost here typically falls around 04/19, about 234 days from today. The first fall frost typically arrives around 10/20, about 182 frost-free days later.
The USDA Plant Hardiness Zone Map puts St. Mary in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 6b around St. Mary has about 8 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around St. Mary's last frost
04/19 is the middle of 30 years of NOAA records, not a promise. Plant by 04/03 and you're betting against frost in roughly 9 years out of 10. 05/03 is the safer bet, historically only a 1-in-10 chance of frost that late.
How St. Mary compares
About 182 days separate St. Mary's last and first frost, putting it 24,309 of 40,283 ZIP codes nationally. Within MO, it ranks 975 of 1,129.
Learn more
local microclimates explains what one yard in St. Mary can differ from the 63673 normal, and zone vs. frost date explains why Zone 6b and St. Mary's frost date answer different questions.