Lake Mercer Weather Forecast

    • 69
    • 87

    Chance Thunderstorms

    • 68
    • 83

    Rain Showers

    • 67
    • 84

    Slight Chance Thunderstorms

    • 67
    • 84

    Mostly Sunny

    • 69
    • 86

    Partly Sunny

    • 70
    • 88

    Chance Rain Showers

Today 27 Jul Fairfax

Mostly sunny. A chance of Showers and Thunderstorms in the afternoon. Highs in the upper 80s. Southwest Winds around 5 Mph. Chance of rain 40 percent.

Tonight 27 Jul Fairfax

Partly cloudy with a slight chance of Showers and Thunderstorms in the Evening, then mostly cloudy after midnight. Lows in the upper 60s. South Winds around 5 Mph. Chance of rain 20 percent.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Lake Mercer Temperature Statistics

July Temperature

Fort Belvoir (4.3 miles)

  • Lowest 24 July, 2026

    57.6 °F

  • Average July

    80.4 °F

  • Highest 4 July, 2026

    101.3 °F

Climate (2021–2026)

Fort Belvoir (4.3 miles)

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  • Average Low 2021–2026

    47.7 °F

  • Average 2021–2026

    58.1 °F

  • Average High 2021–2026

    68.3 °F
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