National Weather Service Forecast for: Johnston IA
Issued by: National Weather Service Des Moines, IA
Updated: 9:27 pm CDT Sep 12, 2026
 
Tonight

Tonight: Partly cloudy, with a low around 57. Light north wind.
Partly Cloudy

 Sunday

Sunday: A 50 percent chance of showers, mainly before 3pm. Increasing clouds, with a high near 70. Calm wind becoming east northeast 5 to 8 mph in the morning. New precipitation amounts of less than a tenth of an inch possible.
Chance
Showers
 Sunday
Night
Sunday Night: A chance of showers between 4am and 5am. Mostly cloudy, with a low around 57. East wind 3 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.
Mostly Cloudy
then Chance
Showers
 Monday

Monday: A chance of showers and thunderstorms before 7am, then showers and possibly a thunderstorm between 7am and 1pm, then a slight chance of showers and thunderstorms after 1pm. High near 81. Breezy, with an east southeast wind 13 to 18 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Showers and
Breezy
 Monday
Night
Monday Night: Showers and possibly a thunderstorm. Low around 68. South southeast wind 7 to 15 mph becoming west after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Showers
Likely then
Showers
 Tuesday

Tuesday: Showers and possibly a thunderstorm. High near 76. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Showers

 Tuesday
Night
Tuesday Night: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Low around 60. Chance of precipitation is 80%.
Chance
T-storms then
Showers
 Wednesday

Wednesday: Showers and possibly a thunderstorm. High near 68. Chance of precipitation is 90%.
Showers

 Wednesday
Night
Wednesday Night: Showers and possibly a thunderstorm. Low around 63. Chance of precipitation is 80%.
Showers
Lo 57 °F Hi 70 °F Lo 57 °F Hi 81 °F Lo 68 °F Hi 76 °F Lo 60 °F Hi 68 °F Lo 63 °F

 

Tonight
 
 Partly cloudy, with a low around 57. Light north wind.
Sunday
 
 A 50 percent chance of showers, mainly before 3pm. Increasing clouds, with a high near 70. Calm wind becoming east northeast 5 to 8 mph in the morning. New precipitation amounts of less than a tenth of an inch possible.
Sunday Night
 
 A chance of showers between 4am and 5am. Mostly cloudy, with a low around 57. East wind 3 to 8 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.
Monday
 
 A chance of showers and thunderstorms before 7am, then showers and possibly a thunderstorm between 7am and 1pm, then a slight chance of showers and thunderstorms after 1pm. High near 81. Breezy, with an east southeast wind 13 to 18 mph, with gusts as high as 30 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Monday Night
 
 Showers and possibly a thunderstorm. Low around 68. South southeast wind 7 to 15 mph becoming west after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Tuesday
 
 Showers and possibly a thunderstorm. High near 76. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Tuesday Night
 
 A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1am. Low around 60. Chance of precipitation is 80%.
Wednesday
 
 Showers and possibly a thunderstorm. High near 68. Chance of precipitation is 90%.
Wednesday Night
 
 Showers and possibly a thunderstorm. Low around 63. Chance of precipitation is 80%.
Thursday
 
 Showers likely before 1pm. Mostly cloudy, with a high near 73. Chance of precipitation is 60%.
Thursday Night
 
 A 50 percent chance of showers. Mostly cloudy, with a low around 59.
Friday
 
 A 50 percent chance of showers. Partly sunny, with a high near 74.
Friday Night
 
 A 40 percent chance of showers. Mostly cloudy, with a low around 58.
Saturday
 
 Partly sunny, with a high near 71.

 

Forecast from NOAA-NWS for Johnston IA.