Grand Lake St. Marys SPB Weather Forecast

    • 67
    • 81

    Rain Showers Likely

    • 66
    • 84

    Mostly Sunny

    • 69
    • 87

    Mostly Sunny

    • 72
    • 90

    Mostly Sunny

    • 72
    • 93

    Mostly Sunny

    • 70
    • 89

    Slight Chance Thunderstorms

Today 11 Jul Mercer

Mostly cloudy with Showers likely with a chance of Thunderstorms. Highs in the lower 80s. Northeast Winds around 5 Mph. Chance of rain 70 percent.

Tonight 11 Jul Mercer

Mostly cloudy with a chance of Showers and Thunderstorms in the Evening, then partly cloudy after midnight. Lows in the mid 60s. Northeast Winds 5 to 10 Mph. Chance of rain 50 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Grand Lake St. Marys SPB Temperature Statistics

July Temperature

Versailles Darke County Airport (23 miles)

  • Lowest 8 July, 2026

    62.6 °F

  • Average July

    77.9 °F

  • Highest 3 July, 2026

    93.2 °F

Climate (2021–2026)

Versailles Darke County Airport (23 miles)

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  • Average Low 2021–2026

    43.3 °F

  • Average 2021–2026

    52.5 °F

  • Average High 2021–2026

    61.8 °F
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