Defiance, MO Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Defiance, a community in St. Charles County, Missouri.
Today
90°F
Areas Of Fog then Sunny
Areas of fog before 9am. Sunny, with a high near 90. South wind around 2 mph.
7-day forecast for Defiance
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 90°F | Areas Of Fog then Sunny | 2 mph S | 0% |
| Tonight | 68°F | Mostly Clear | 2 mph S | 0% |
| Wednesday | 91°F | Sunny | 3 mph S | 14% |
| Wednesday Night | 71°F | Chance Showers And Thunderstorms | 3 mph S | 68% |
| Thursday | 87°F | Showers And Thunderstorms Likely | 2 mph S | 69% |
| Thursday Night | 69°F | Mostly Cloudy then Chance Showers And Thunderstorms | 1 mph SE | 28% |
| Friday | 88°F | Chance Showers And Thunderstorms then Partly Sunny | 1 mph SW | 28% |
| Friday Night | 70°F | Chance Showers And Thunderstorms | 1 mph S | 28% |
| Saturday | 90°F | Chance Showers And Thunderstorms then Mostly Sunny | 2 mph SW | 28% |
| Saturday Night | 72°F | Mostly Clear | 3 mph S | 6% |
| Sunday | 92°F | Sunny | 5 mph SW | 4% |
| Sunday Night | 73°F | Mostly Clear | 5 mph S | 5% |
| Monday | 94°F | Sunny | 6 mph SW | 4% |
| Monday Night | 75°F | Partly Cloudy | 5 mph S | 14% |
Forecast source: National Weather Service (api.weather.gov) for Defiance (38.633, -90.785). Updated through the day.
Growing snapshot for Defiance
Last spring frost
Apr 10
First fall frost
Oct 26
Growing season
199 days
Hardiness zone
6b
More local growing data for Defiance: nearby ZIP 63341 weather · frost dates · planting calendar · Missouri frost dates
Nearby towns & communities
Augusta
Cottleville
Dardenne Prairie
Flint Hill
Foristell
Josephville
Lake St. Louis
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 (7.2 mi from Defiance). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.