National Weather Service Forecast for: Johnston IA
Issued by: National Weather Service Des Moines, IA
Updated: 3:37 am CDT Jun 22, 2026
 
Today

Today: Mostly sunny, with a high near 77. Calm wind becoming east northeast around 5 mph.
Mostly Sunny

 Tonight

Tonight: Mostly clear, with a low around 57. Light and variable wind.
Mostly Clear

 Tuesday

Tuesday: Increasing clouds, with a high near 78. Calm wind becoming south 5 to 8 mph in the afternoon.
Increasing
Clouds
 Tuesday
Night
Tuesday Night: A 40 percent chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 62. South wind around 6 mph becoming calm in the evening. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Mostly Cloudy
then Chance
T-storms
 Wednesday

Wednesday: A chance of thunderstorms before 7am. Mostly sunny, with a high near 81. Light west wind becoming west northwest 5 to 9 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Chance
T-storms then
Sunny
 Wednesday
Night
Wednesday Night: Partly cloudy, with a low around 59.
Partly Cloudy

 Thursday

Thursday: Mostly sunny, with a high near 78.
Mostly Sunny

 Thursday
Night
Thursday Night: Partly cloudy, with a low around 58.
Partly Cloudy

 Friday

Friday: Mostly sunny, with a high near 79.
Mostly Sunny
Hi 77 °F Lo 57 °F Hi 78 °F Lo 62 °F Hi 81 °F Lo 59 °F Hi 78 °F Lo 58 °F Hi 79 °F

 

Today
 
 Mostly sunny, with a high near 77. Calm wind becoming east northeast around 5 mph.
Tonight
 
 Mostly clear, with a low around 57. Light and variable wind.
Tuesday
 
 Increasing clouds, with a high near 78. Calm wind becoming south 5 to 8 mph in the afternoon.
Tuesday Night
 
 A 40 percent chance of showers and thunderstorms after 1am. Mostly cloudy, with a low around 62. South wind around 6 mph becoming calm in the evening. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday
 
 A chance of thunderstorms before 7am. Mostly sunny, with a high near 81. Light west wind becoming west northwest 5 to 9 mph in the morning. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday Night
 
 Partly cloudy, with a low around 59.
Thursday
 
 Mostly sunny, with a high near 78.
Thursday Night
 
 Partly cloudy, with a low around 58.
Friday
 
 Mostly sunny, with a high near 79.
Friday Night
 
 Mostly cloudy, with a low around 62.
Saturday
 
 Partly sunny, with a high near 84.
Saturday Night
 
 A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 70.
Sunday
 
 Mostly sunny, with a high near 91. Breezy.

 

Forecast from NOAA-NWS for Johnston IA.