Grand Lake St. Marys SPB Weather Forecast

    • 73
    • 91

    Mostly Sunny

    • 74
    • 91

    Chance Thunderstorms

    • 69
    • 85

    Thunderstorms Likely

    • 70
    • 86

    Slight Chance Thunderstorms

    • 70
    • 87

    Chance Thunderstorms

    • 68
    • 84

    Chance Thunderstorms

    • 70
    • 86

    Chance Thunderstorms

Today 5 Jul Mercer

Mostly sunny. Near steady Temperatures around 90. Southwest Winds 5 to 10 Mph.

Tonight 5 Jul Mercer

Clear. Lows in the lower 70s. South Winds 5 to 10 Mph.

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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 2 July, 2025

    64.4 °F

  • Average July

    77.4 °F

  • Highest 3 July, 2025

    86 °F

Climate (2020–Present)

Versailles Darke County Airport (23 miles)

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  • Average Low 2020–2025

    43.3 °F

  • Average 2020–2025

    52.4 °F

  • Average High 2020–2025

    61.6 °F
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