Union Weather Forecast

    • 69
    • 93

    Mostly Sunny

    • 68
    • 90

    Mostly Sunny

    • 66
    • 85

    Chance Rain Showers

    • 69
    • 86

    Partly Sunny

    • 70
    • 93

    Rain Showers Likely

    • 65
    • 89

    Chance Rain Showers

Today 4 Sep Hardin

Mostly Sunny, then becoming mostly sunny this Morning, then becoming sunny. A slight chance of Showers and Thunderstorms this morning. Humid with Highs in the lower 90s. South Winds 5 to 10 Mph. Chance of rain 20 percent. Heat index Values up to 105.

Tonight 4 Sep Hardin

Partly cloudy in the Evening, then becoming mostly clear. Humid with Lows in the upper 60s. Southeast Winds around 5 Mph. Heat index Values up to 102 early in the evening.

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Union Temperature Statistics

September Temperature

Marshalltown, Marshalltown Municipal Airport (11.8 miles)

  • Lowest 1 September, 2026

    70 °F

  • Average September

    80.5 °F

  • Highest 1 September, 2026

    91 °F

Climate (2021–2026)

Marshalltown, Marshalltown Municipal Airport (11.8 miles)

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  • Average Low 2021–2026

    39.7 °F

  • Average 2021–2026

    50.6 °F

  • Average High 2021–2026

    61.4 °F
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