National Weather Service Forecast for: Arnold MO
Issued by: National Weather Service Saint Louis, MO
Updated: 11:30 pm CDT Jun 18, 2026
 
Tonight

Tonight: Partly cloudy, with a low around 62. Calm wind.
Partly Cloudy

 Juneteenth

Juneteenth: Sunny, with a high near 84. Light and variable wind.
Sunny

 Friday
Night
Friday Night: Partly cloudy, with a low around 64. Calm wind.
Partly Cloudy

 Saturday

Saturday: Mostly sunny, with a high near 87. Light and variable wind.
Mostly Sunny

 Saturday
Night
Saturday Night: A chance of showers between 1am and 4am, then a chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 67. Light southeast wind. Chance of precipitation is 30%.
Mostly Clear
then Chance
Showers
 Sunday

Sunday: Showers and possibly a thunderstorm. High near 85. Chance of precipitation is 80%.
Showers
Likely then
T-storms
 Sunday
Night
Sunday Night: Showers and possibly a thunderstorm before 1am, then showers likely. Low around 66. Chance of precipitation is 90%.
Showers

 Monday

Monday: A 30 percent chance of showers and thunderstorms before 1pm. Mostly cloudy, with a high near 80.
Chance
Showers
 Monday
Night
Monday Night: Partly cloudy, with a low around 61.
Partly Cloudy
Lo 62 °F Hi 84 °F Lo 64 °F Hi 87 °F Lo 67 °F Hi 85 °F Lo 66 °F Hi 80 °F Lo 61 °F

 

Tonight
 
 Partly cloudy, with a low around 62. Calm wind.
Juneteenth
 
 Sunny, with a high near 84. Light and variable wind.
Friday Night
 
 Partly cloudy, with a low around 64. Calm wind.
Saturday
 
 Mostly sunny, with a high near 87. Light and variable wind.
Saturday Night
 
 A chance of showers between 1am and 4am, then a chance of showers and thunderstorms after 4am. Partly cloudy, with a low around 67. Light southeast wind. Chance of precipitation is 30%.
Sunday
 
 Showers and possibly a thunderstorm. High near 85. Chance of precipitation is 80%.
Sunday Night
 
 Showers and possibly a thunderstorm before 1am, then showers likely. Low around 66. Chance of precipitation is 90%.
Monday
 
 A 30 percent chance of showers and thunderstorms before 1pm. Mostly cloudy, with a high near 80.
Monday Night
 
 Partly cloudy, with a low around 61.
Tuesday
 
 Mostly sunny, with a high near 82.
Tuesday Night
 
 A 20 percent chance of showers. Partly cloudy, with a low around 63.
Wednesday
 
 Mostly sunny, with a high near 84.
Wednesday Night
 
 A 20 percent chance of showers. Mostly clear, with a low around 63.
Thursday
 
 A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 84.

 

Forecast from NOAA-NWS for Arnold MO.