Mount Sinai Harbor Weather Forecast

    • 68
    • 77

    Sunny

    • 61
    • 78

    Mostly Sunny

    • 60
    • 69

    Mostly Sunny

    • 60
    • 68

    Partly Sunny

    • 66
    • 72

    Partly Sunny

    • 67
    • 77

    Slight Chance Rain Showers

Today 18 Sep Northwest Suffolk

Patchy fog this morning. Partly sunny with a slight chance of Showers this Morning, then sunny this afternoon. Highs in the upper 70s. North Winds around 5 Mph, becoming northwest this afternoon. Chance of rain 20 percent.

Tonight 18 Sep Northwest Suffolk

Mostly clear. Lows in the lower 60s. Southwest Winds around 5 Mph, becoming northwest after midnight.

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  • Temperature Forecast NOAA

  • Temperature Real-Time

Mount Sinai Harbor Temperature Statistics

September Temperature

Islip, Long Island Mac Arthur Airport (11.8 miles)

  • Lowest 9 September, 2025

    54 °F

  • Average September

    69.3 °F

  • Highest 6 September, 2025

    81 °F

Climate (2020–Present)

Islip, Long Island Mac Arthur Airport (11.8 miles)

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  • Average Low 2020–2025

    47.4 °F

  • Average 2020–2025

    55.2 °F

  • Average High 2020–2025

    63.1 °F
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