Lake St. Louis, MO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Lake St. Louis, a city in St. Charles County, Missouri.
This Afternoon
96°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Sunny, with a high near 96. Heat index values as high as 107. South wind around 2 mph. Chance of precipitation is 30%.
7-day forecast for Lake St. Louis
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 96°F | Chance Showers And Thunderstorms | 2 mph S | 26% |
| Tonight | 73°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 3 mph SE | 21% |
| Saturday | 97°F | Partly Sunny | 3 to 7 mph SW | 5% |
| Saturday Night | 72°F | Partly Cloudy | 3 mph SW | 6% |
| Sunday | 91°F | Chance Rain Showers then Chance Showers And Thunderstorms | 5 mph W | 32% |
| Sunday Night | 66°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 6 mph N | 67% |
| Monday | 78°F | Showers And Thunderstorms Likely | 5 to 8 mph N | 69% |
| Monday Night | 59°F | Showers And Thunderstorms Likely | 8 mph N | 63% |
| Tuesday | 71°F | Slight Chance Rain Showers then Mostly Cloudy | 9 mph N | 23% |
| Tuesday Night | 53°F | Mostly Cloudy | 3 to 8 mph N | 5% |
| Wednesday | 73°F | Mostly Sunny | 6 mph N | 0% |
| Wednesday Night | 54°F | Partly Cloudy | 1 to 5 mph N | 1% |
| Thursday | 75°F | Mostly Sunny | 2 to 6 mph N | 3% |
| Thursday Night | 57°F | Partly Cloudy | 1 to 5 mph NE | 3% |
Forecast source: National Weather Service (api.weather.gov) for Lake St. Louis (38.780, -90.786). Updated through the day.
Growing snapshot for Lake St. Louis
Last spring frost
Apr 10
First fall frost
Oct 26
Growing season
199 days
Hardiness zone
6b
More local growing data for Lake St. Louis: nearby ZIP 63367 weather · frost dates · planting calendar · Missouri frost dates
Nearby towns & communities
Augusta
Cottleville
Dardenne Prairie
Defiance
Flint Hill
Foristell
Josephville
New Melle
O'Fallon
St. Paul
St. Peters
Weldon Spring
Weldon Spring Heights
Wentzville
West Alton
Climate data from the nearest NOAA station, Weldon Spring Nws, Mo (8 mi from Lake St. Louis). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.