Johnston Weather Forecast

    • 73
    • 93

    Slight Chance Thunderstorms

    • 75
    • 94

    Mostly Sunny

    • 74
    • 94

    Chance Thunderstorms

    • 73
    • 91

    Slight Chance Thunderstorms

    • 70
    • 91

    Partly Sunny

    • 69
    • 90

    Partly Sunny

Today 31 Aug Polk

Mostly sunny with a slight chance of Showers and Thunderstorms. Humid with Highs in the mid 90s. Southwest Winds 5 to 10 Mph. Chance of rain 20 percent. Heat index Values up to 103 in the afternoon.

Tonight 31 Aug Polk

Partly cloudy in the Evening, then mostly cloudy with a slight chance of Showers and Thunderstorms after midnight. Humid with Lows in the mid 70s. Southwest Winds around 5 Mph, becoming southeast after midnight. Chance of rain 20 percent. Heat index Values up to 102 early in the evening.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Johnston Temperature Statistics

August Temperature

Ankeny Regional Airport (6.8 miles)

  • Lowest 23 August, 2026

    55.4 °F

  • Average August

    73.6 °F

  • Highest 11 August, 2026

    93.2 °F

Climate (2021–2026)

Ankeny Regional Airport (6.8 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    41.4 °F

  • Average 2021–2026

    52.1 °F

  • Average High 2021–2026

    62.3 °F
Get WillyWeather+ to remove ads