Grand Lake Saint Marys State Park Weather Forecast

    • 68
    • 84

    Chance Thunderstorms

    • 66
    • 85

    Rain Showers

    • 66
    • 84

    Chance Thunderstorms

    • 68
    • 85

    Chance Thunderstorms

    • 70
    • 84

    Rain Showers Likely

    • 72
    • 86

    Chance Thunderstorms

Today 5 Jun Mercer

Mostly sunny. Highs in the mid 80s. Southwest Winds 15 to 20 Mph with Gusts up to 30 Mph.

Tonight 5 Jun Mercer

Partly cloudy in the Evening, then mostly cloudy with Showers likely with a chance of Thunderstorms after midnight. Lows in the upper 60s. Southwest Winds 15 to 20 Mph with Gusts up to 30 Mph. Chance of rain 70 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Grand Lake Saint Marys State Park Temperature Statistics

June Temperature

Versailles Darke County Airport (22.4 miles)

  • Lowest 3 June, 2026

    50 °F

  • Average June

    65.5 °F

  • Highest 3 June, 2026

    80.6 °F

Climate (2021–Present)

Versailles Darke County Airport (22.4 miles)

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  • Average Low 2021–2026

    43.3 °F

  • Average 2021–2026

    52.5 °F

  • Average High 2021–2026

    61.7 °F
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