Lake St. Louis, MO Weather & Growing Conditions
Today
97°F
Partly Sunny
Partly sunny, with a high near 97. Heat index values as high as 100. Southwest wind 5 to 8 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 97°F | Partly Sunny | 5 to 8 mph SW | 1% |
| Tonight | 73°F | Partly Cloudy | 1 to 5 mph SW | 4% |
| Sunday | 90°F | Chance Rain Showers then Slight Chance Showers And Thunderstorms | 2 to 6 mph W | 43% |
| Sunday Night | 66°F | Showers And Thunderstorms Likely | 7 mph N | 72% |
| Monday | 76°F | Showers And Thunderstorms Likely | 6 to 10 mph NE | 72% |
| Monday Night | 58°F | Chance Showers And Thunderstorms | 6 to 10 mph NE | 30% |
| Tuesday | 69°F | Slight Chance Rain Showers then Mostly Cloudy | 8 to 12 mph N | 19% |
| Tuesday Night | 53°F | Mostly Cloudy | 3 to 9 mph N | 2% |
| Wednesday | 73°F | Mostly Sunny | 5 to 8 mph N | 1% |
| Wednesday Night | 54°F | Partly Cloudy | 1 to 6 mph N | 0% |
| Thursday | 75°F | Mostly Sunny | 2 to 6 mph NE | 3% |
| Thursday Night | 57°F | Mostly Cloudy | 1 to 6 mph NE | 4% |
| Friday | 76°F | Partly Sunny | 2 to 6 mph NE | 8% |
| Friday Night | 57°F | Partly Cloudy | 1 to 5 mph NE | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Lake St. Louis, MO
Last spring frost
Apr 10
First fall frost
Oct 26
Growing season
199 days
Hardiness zone
6b
Explore more for Lake St. Louis, MO: full frost dates · planting calendar · Missouri frost dates
Climate data from the nearest NOAA station, Weldon Spring Nws, Mo (8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.