St. Mary, MO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. Mary, a city in Ste. Genevieve County, Missouri.
This Afternoon
98°F
Mostly Sunny
Mostly sunny, with a high near 98. West southwest wind 5 to 8 mph.
7-day forecast for St. Mary
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 98°F | Mostly Sunny | 5 to 8 mph WSW | 1% |
| Tonight | 72°F | Mostly Clear | 5 mph SSW | 2% |
| Sunday | 95°F | Mostly Sunny | 5 mph WSW | 2% |
| Sunday Night | 67°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 5 mph N | 42% |
| Monday | 85°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 3 to 8 mph NE | 65% |
| Monday Night | 60°F | Showers And Thunderstorms Likely | 5 to 8 mph N | 65% |
| Tuesday | 73°F | Chance Showers And Thunderstorms | 7 to 12 mph N | 34% |
| Tuesday Night | 54°F | Mostly Cloudy | 5 to 12 mph N | 9% |
| Wednesday | 75°F | Mostly Sunny | 9 mph N | 2% |
| Wednesday Night | 53°F | Partly Cloudy | 2 to 8 mph N | 1% |
| Thursday | 77°F | Mostly Sunny | 2 to 8 mph N | 3% |
| Thursday Night | 56°F | Partly Cloudy | 2 to 6 mph NNE | 4% |
| Friday | 78°F | Mostly Sunny | 2 to 8 mph NNE | 5% |
| Friday Night | 56°F | Partly Cloudy | 2 to 6 mph NNE | 5% |
Forecast source: National Weather Service (api.weather.gov) for St. Mary (37.874, -89.950). Updated through the day.
Growing snapshot for St. Mary
Last spring frost
Apr 19
First fall frost
Oct 20
Growing season
182 days
Hardiness zone
6b
More local growing data for St. Mary: nearby ZIP 63673 weather · frost dates · planting calendar · Missouri frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Perryville Wtp, Mo (8.4 mi from St. Mary). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.