National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

The Florida Keys - Marathon International Airport (KMTH)

Lat: 24.73°NLon: 81.05°WElev: 13ft.

Fair

86°F

30°C

Humidity 77%
Wind Speed SE 3 mph
Barometer 29.94 in (1013.9 mb)
Dewpoint 78°F (26°C)
Visibility 10.00 mi
Heat Index98°F (37°C)
Last update 4 Sep 1:53 am EDT
Extended Forecast for

23 Miles NNW Long Key FL

  • Overnight

    Overnight: Partly cloudy, with a low around 78. Light southeast wind.

    Low: 78 °F

    Partly Cloudy

  • Friday

    Friday: A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91. Heat index values as high as 103. Southeast wind 3 to 6 mph. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 91 °F

    Chance
    T-storms

  • Friday Night

    Friday Night: A 40 percent chance of showers and thunderstorms, mainly before 2am. Partly cloudy, with a low around 77. East wind 3 to 5 mph.

    Low: 77 °F

    Chance
    T-storms

  • Saturday

    Saturday: Showers and thunderstorms likely, mainly between 2pm and 5pm. Mostly sunny, with a high near 90. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon. Chance of precipitation is 60%.

    High: 90 °F

    T-storms
    Likely

  • Saturday Night

    Saturday Night: Showers and thunderstorms likely, mainly before 8pm. Mostly cloudy, with a low around 77. Calm wind. Chance of precipitation is 60%.

    Low: 77 °F

    T-storms
    Likely

  • Sunday

    Sunday: A chance of showers and thunderstorms before 8am, then showers likely and possibly a thunderstorm between 8am and 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 90. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 70%.

    High: 90 °F

    Showers
    Likely

  • Sunday Night

    Sunday Night: A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 77. Calm wind.

    Low: 77 °F

    Chance
    T-storms

  • Labor Day

    Labor Day: Showers and thunderstorms likely, mainly after 2pm. Mostly sunny, with a high near 90. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 60%.

    High: 90 °F

    T-storms
    Likely

  • Monday Night

    Monday Night: Showers and thunderstorms likely, mainly before 8pm. Partly cloudy, with a low around 80. Light and variable wind. Chance of precipitation is 60%.

    Low: 80 °F

    T-storms
    Likely

Detailed Forecast

Overnight
Partly cloudy, with a low around 78. Light southeast wind.
Friday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 91. Heat index values as high as 103. Southeast wind 3 to 6 mph. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Friday Night
A 40 percent chance of showers and thunderstorms, mainly before 2am. Partly cloudy, with a low around 77. East wind 3 to 5 mph.
Saturday
Showers and thunderstorms likely, mainly between 2pm and 5pm. Mostly sunny, with a high near 90. Heat index values as high as 102. Calm wind becoming southeast around 5 mph in the afternoon. Chance of precipitation is 60%.
Saturday Night
Showers and thunderstorms likely, mainly before 8pm. Mostly cloudy, with a low around 77. Calm wind. Chance of precipitation is 60%.
Sunday
A chance of showers and thunderstorms before 8am, then showers likely and possibly a thunderstorm between 8am and 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 90. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 70%.
Sunday Night
A 40 percent chance of showers and thunderstorms. Partly cloudy, with a low around 77. Calm wind.
Labor Day
Showers and thunderstorms likely, mainly after 2pm. Mostly sunny, with a high near 90. Calm wind becoming southwest around 5 mph in the afternoon. Chance of precipitation is 60%.
Monday Night
Showers and thunderstorms likely, mainly before 8pm. Partly cloudy, with a low around 80. Light and variable wind. Chance of precipitation is 60%.
Tuesday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 88.
Tuesday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 80.
Wednesday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89.
Wednesday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 80.
Thursday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 88.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
23 Miles NNW Long Key FL
 25.14°N 80.95°W
Last Update:
2:31 am EDT Sep 4, 2026
Forecast Valid:
2am EDT Sep 4, 2026-6pm EDT Sep 10, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation