Merrimac Weather Forecast

    • 63
    • 92

    Becoming Sunny

    • 62
    • 91

    Mostly Sunny

    • 72
    • 96

    Mostly Sunny

    • 70
    • 99

    Chance Rain Showers

    • 63
    • 86

    Slight Chance Thunderstorms

    • 63
    • 87

    Chance Rain Showers

Today 6 Sep Monroe

Sunny. Not as warm with Highs in the lower 90s. Northeast Winds 5 to 10 Mph.

Tonight 6 Sep Monroe

Partly cloudy. Lows in the lower 60s. Northeast Winds 5 to 10 Mph.

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  • Temperature Real-Time

Merrimac Temperature Statistics

September Temperature

St. Louis Downtown Airport (16.2 miles)

  • Lowest 1 September, 2026

    70.6 °F

  • Average September

    86.6 °F

  • Highest 1 September, 2026

    100.7 °F

Climate (2021–2026)

St. Louis Downtown Airport (16.2 miles)

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  • Average Low 2021–2026

    47.7 °F

  • Average 2021–2026

    58.6 °F

  • Average High 2021–2026

    69.4 °F
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