Herndon Weather Forecast

    • 72
    • 91

    Chance Thunderstorms

    • 70
    • 91

    Partly Sunny

    • 72
    • 92

    Mostly Sunny

    • 70
    • 90

    Chance Thunderstorms

    • 70
    • 88

    Chance Thunderstorms

    • 69
    • 87

    Slight Chance Thunderstorms

Today 8 Aug Eastern Loudoun

Mostly sunny with scattered Showers and Thunderstorms. Some Thunderstorms may be severe with damaging Winds, large Hail, and heavy rainfall. Highs around 90. Southwest Winds 5 to 10 Mph. Chance of rain 50 percent.

Tonight 8 Aug Eastern Loudoun

Partly cloudy. Scattered Showers and Thunderstorms in the evening. Some Thunderstorms may produce heavy rainfall in the evening. Lows in the lower 70s. Southwest Winds around 5 Mph. Chance of rain 40 percent.

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Herndon Temperature Statistics

August Temperature

Washington/Dulles International Airport, DC (4.3 miles)

  • Lowest 1 August, 2026

    65.6 °F

  • Average August

    79.3 °F

  • Highest 6 August, 2026

    91 °F

Climate (2021–2026)

Washington/Dulles International Airport, DC (4.3 miles)

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  • Average Low 2021–2026

    47.6 °F

  • Average 2021–2026

    58.3 °F

  • Average High 2021–2026

    68.6 °F
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