Lostmans River - Onion Key Weather Forecast

    • 63
    • 82

    Decreasing Clouds

    • 65
    • 84

    Mostly Sunny

    • 64
    • 83

    Partly Sunny

    • 64
    • 81

    Mostly Sunny

    • 62
    • 79

    Mostly Sunny

    • 62
    • 80

    Mostly Sunny

Today 19 Dec Mainland Monroe

Partly sunny. A slight chance of Showers this morning. Patchy fog this morning. Highs in the lower 80s. Southwest Winds 5 to 10 Mph, becoming west this afternoon. Chance of rain 20 percent.

Tonight 19 Dec Mainland Monroe

Partly cloudy in the Evening, then becoming mostly clear. Lows in the lower 60s. Northwest Winds 5 to 10 Mph.

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Lostmans River - Onion Key Temperature Statistics

December Temperature

Miami, Kendall-Tamiami Executive Airport (43.5 miles)

  • Lowest 11 December, 2025

    54 °F

  • Average December

    71.7 °F

  • Highest 6 December, 2025

    84.9 °F

Climate (2020–Present)

Miami, Kendall-Tamiami Executive Airport (43.5 miles)

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  • Average Low 2020–2025

    69.4 °F

  • Average 2020–2025

    77.3 °F

  • Average High 2020–2025

    85.7 °F
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