Grand Lake St. Marys SPB Weather Forecast

    • 62
    • 86

    Mostly Sunny

    • 63
    • 87

    Mostly Sunny

    • 65
    • 85

    Mostly Cloudy

    • 67
    • 85

    Chance Rain Showers

    • 66
    • 78

    Chance Rain Showers

    • 62
    • 80

    Chance Rain Showers

Today 18 Sep Mercer

Sunny. Highs in the upper 80s. Light and variable Winds, becoming northwest around 5 Mph late.

Tonight 18 Sep Mercer

Mostly clear. Lows around 60. Northeast Winds around 5 Mph in the Evening, becoming light and variable.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Grand Lake St. Marys SPB Temperature Statistics

September Temperature

Versailles Darke County Airport (23 miles)

  • Lowest 12 September, 2025

    48.2 °F

  • Average September

    70.3 °F

  • Highest 15 September, 2025

    87.8 °F

Climate (2020–Present)

Versailles Darke County Airport (23 miles)

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  • Average Low 2020–2025

    43.2 °F

  • Average 2020–2025

    52.2 °F

  • Average High 2020–2025

    61.3 °F
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