Grand Lake Saint Marys State Park Weather Forecast

    • 62
    • 79

    Partly Sunny

    • 68
    • 83

    Slight Chance Thunderstorms

    • 69
    • 85

    Rain Showers Likely

    • 70
    • 83

    Rain Showers Likely

    • 64
    • 81

    Chance Thunderstorms

    • 69
    • 83

    Partly Sunny

Today 15 Jun Mercer

Partly cloudy. Highs in the upper 70s. Northeast Winds 5 to 10 Mph.

Tonight 15 Jun Mercer

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

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Grand Lake Saint Marys State Park Temperature Statistics

June Temperature

Versailles Darke County Airport (22.4 miles)

  • Lowest 1 June, 2025

    41 °F

  • Average June

    69.1 °F

  • Highest 3 June, 2025

    86 °F

Climate (2020–Present)

Versailles Darke County Airport (22.4 miles)

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  • Average Low 2020–2025

    43.2 °F

  • Average 2020–2025

    52.3 °F

  • Average High 2020–2025

    61.6 °F
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