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.
Today
98°F
Mostly Sunny
Mostly sunny. High near 98, with temperatures falling to around 96 in the afternoon. Southwest wind 3 to 7 mph.
7-day forecast for St. Mary
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 98°F | Mostly Sunny | 3 to 7 mph SW | 1% |
| Tonight | 72°F | Mostly Clear | 6 mph SSW | 2% |
| Sunday | 95°F | Mostly Sunny | 5 mph W | 13% |
| Sunday Night | 67°F | Slight Chance Showers And Thunderstorms | 5 mph N | 46% |
| Monday | 82°F | Showers And Thunderstorms Likely | 3 to 8 mph N | 64% |
| Monday Night | 59°F | Showers And Thunderstorms Likely then Slight Chance Showers And Thunderstorms | 6 to 9 mph N | 64% |
| Tuesday | 73°F | Slight Chance Showers And Thunderstorms | 7 to 12 mph N | 23% |
| 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.