Big Trinity Lake Weather Forecast

    • 37
    • 56

    Increasing Clouds

    • 40
    • 62

    Chance Rain Showers

    • 36
    • 56

    Rain Showers Likely

    • 35
    • 55

    Mostly Sunny

    • 37
    • 58

    Mostly Sunny

    • 39
    • 61

    Mostly Sunny

Today 15 Sep Boise Mountains

Areas of fog this morning. Sunny. Highs 63 to 77.

Tonight 15 Sep Boise Mountains

Partly cloudy. Lows 34 to 49.

Graph Plots Open in Graphs

  • Temperature Forecast NOAA

  • Temperature Real-Time

Big Trinity Lake Temperature Statistics

September Temperature

Boise Air Terminal (40.4 miles)

  • Lowest 3 September, 2026

    46.7 °F

  • Average September

    65.8 °F

  • Highest 12 September, 2026

    90.6 °F

Climate (2021–2026)

Boise Air Terminal (40.4 miles)

Take a look at our website widgetsAvailable free! Find Out More

  • Average Low 2021–2026

    44.1 °F

  • Average 2021–2026

    54.9 °F

  • Average High 2021–2026

    66.3 °F
Get WillyWeather+ to remove ads