Old Mastic Weather Forecast

    • 66
    • 76

    Rain Showers

    • 58
    • 72

    Chance Rain Showers

    • 58
    • 69

    Mostly Sunny

    • 63
    • 72

    Partly Sunny

    • 65
    • 75

    Partly Sunny

    • 61
    • 75

    Chance Rain Showers

Today 13 Sep Southeast Suffolk

Showers with a chance of Thunderstorms. Some Thunderstorms may produce heavy rainfall. Locally heavy rainfall possible in the morning. Humid with Highs in the mid 70s. Southeast Winds 5 to 10 Mph, becoming west in the afternoon. Chance of rain near 100 percent.

Tonight 13 Sep Southeast Suffolk

Partly cloudy. A slight chance of Showers after midnight. Humid with Lows in the mid 60s. West Winds 5 to 10 Mph. Chance of rain 20 percent.

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Old Mastic Temperature Statistics

September Temperature

Shirley, Brookhaven Airport (3.1 miles)

  • Lowest 7 September, 2026

    53.1 °F

  • Average September

    70.4 °F

  • Highest 10 September, 2026

    84.9 °F

Climate (2021–2026)

Shirley, Brookhaven Airport (3.1 miles)

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  • Average Low 2021–2026

    46.1 °F

  • Average 2021–2026

    54.5 °F

  • Average High 2021–2026

    62.6 °F
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