Boulder Weather Forecast

    • 57
    • 80

    Mostly Sunny

    • 58
    • 84

    Increasing Clouds

    • 55
    • 79

    Mostly Cloudy

    • 57
    • 81

    Mostly Sunny

    • 61
    • 84

    Mostly Sunny

    • 65
    • 92

    Mostly Sunny

    • 64
    • 93

    Mostly Sunny

Today 18 Sep Santa Clara Valley Including San Jose

Partly cloudy in the morning then becoming sunny. Highs in the mid 80s to lower 90s.

Tonight 18 Sep Santa Clara Valley Including San Jose

Mostly clear except patchy fog after midnight. Lows in the mid 50s. Northwest Winds 5 to 15 Mph. Becoming south up to 5 Mph after midnight.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Boulder Temperature Statistics

September Temperature

San Jose / Reid / Hillv (4.3 miles)

  • Lowest 7 September, 2026

    53.6 °F

  • Average September

    73.1 °F

  • Highest 9 September, 2026

    98.6 °F

Climate (2021–2026)

San Jose / Reid / Hillv (4.3 miles)

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  • Average Low 2021–2026

    52.1 °F

  • Average 2021–2026

    63.7 °F

  • Average High 2021–2026

    72.2 °F
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