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

85°F

29°C

Humidity 75%
Wind Speed NE 5 mph
Barometer 29.98 in (1015.1 mb)
Dewpoint 76°F (24°C)
Visibility 10.00 mi
Heat Index95°F (35°C)
Last update 1 Sep 11:53 pm EDT
Extended Forecast for

23 Miles NNW Long Key FL

  • Overnight

    Overnight: A 20 percent chance of showers and thunderstorms before 2am. Partly cloudy, with a low around 78. Calm wind.

    Low: 78 °F

    Slight Chance
    T-storms

  • Wednesday

    Wednesday: A 40 percent chance of showers and thunderstorms, mainly after 2pm. Mostly sunny, with a high near 90. Heat index values as high as 103. Calm wind becoming south around 5 mph in the afternoon.

    High: 90 °F

    Chance
    T-storms

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly between 3am and 4am. Partly cloudy, with a low around 78. Light and variable wind.

    Low: 78 °F

    Chance
    T-storms then
    Chance
    Showers

  • Thursday

    Thursday: Showers and thunderstorms likely, mainly after 2pm. Mostly sunny, with a high near 90. Heat index values as high as 103. Light and variable wind becoming southeast around 6 mph in the afternoon. Chance of precipitation is 70%.

    High: 90 °F

    Chance
    T-storms then
    T-storms
    Likely

  • Thursday Night

    Thursday Night: Showers and thunderstorms likely, mainly before 8pm. Partly cloudy, with a low around 78. East wind around 6 mph. Chance of precipitation is 60%.

    Low: 78 °F

    T-storms
    Likely

  • Friday

    Friday: A chance of showers and thunderstorms before 8am, then showers and possibly a thunderstorm between 8am and 2pm, then showers and thunderstorms likely after 2pm. High near 90. Southeast wind 6 to 8 mph. Chance of precipitation is 80%.

    High: 90 °F

    T-storms

  • Friday Night

    Friday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms after 8pm. Mostly cloudy, with a low around 80. East wind 7 to 9 mph. Chance of precipitation is 60%.

    Low: 80 °F

    Showers
    Likely then
    Chance
    T-storms

  • Saturday

    Saturday: Showers likely and possibly a thunderstorm, then showers and thunderstorms after 2pm. High near 88. East wind around 6 mph. Chance of precipitation is 80%.

    High: 88 °F

    Showers
    Likely then
    T-storms

  • Saturday Night

    Saturday Night: Showers and thunderstorms, mainly before 8pm. Low around 80. East wind around 6 mph. Chance of precipitation is 80%.

    Low: 80 °F

    T-storms then
    Chance
    T-storms

Detailed Forecast

Overnight
A 20 percent chance of showers and thunderstorms before 2am. Partly cloudy, with a low around 78. Calm wind.
Wednesday
A 40 percent chance of showers and thunderstorms, mainly after 2pm. Mostly sunny, with a high near 90. Heat index values as high as 103. Calm wind becoming south around 5 mph in the afternoon.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly between 3am and 4am. Partly cloudy, with a low around 78. Light and variable wind.
Thursday
Showers and thunderstorms likely, mainly after 2pm. Mostly sunny, with a high near 90. Heat index values as high as 103. Light and variable wind becoming southeast around 6 mph in the afternoon. Chance of precipitation is 70%.
Thursday Night
Showers and thunderstorms likely, mainly before 8pm. Partly cloudy, with a low around 78. East wind around 6 mph. Chance of precipitation is 60%.
Friday
A chance of showers and thunderstorms before 8am, then showers and possibly a thunderstorm between 8am and 2pm, then showers and thunderstorms likely after 2pm. High near 90. Southeast wind 6 to 8 mph. Chance of precipitation is 80%.
Friday Night
Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms after 8pm. Mostly cloudy, with a low around 80. East wind 7 to 9 mph. Chance of precipitation is 60%.
Saturday
Showers likely and possibly a thunderstorm, then showers and thunderstorms after 2pm. High near 88. East wind around 6 mph. Chance of precipitation is 80%.
Saturday Night
Showers and thunderstorms, mainly before 8pm. Low around 80. East wind around 6 mph. Chance of precipitation is 80%.
Sunday
Showers likely and possibly a thunderstorm before 2pm, then showers and thunderstorms likely after 2pm. Mostly sunny, with a high near 87. Chance of precipitation is 60%.
Sunday Night
Showers and thunderstorms likely. Partly cloudy, with a low around 80. Chance of precipitation is 60%.
Labor Day
Showers and thunderstorms likely. Mostly sunny, with a high near 87. Chance of precipitation is 60%.
Monday Night
Showers and thunderstorms likely. Mostly cloudy, with a low around 80. Chance of precipitation is 60%.
Tuesday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 88.
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ABOUT THIS FORECAST

 
Point Forecast:
23 Miles NNW Long Key FL
 25.14°N 80.92°W
Last Update:
4:21 pm EDT Sep 1, 2026
Forecast Valid:
12am EDT Sep 2, 2026-6pm EDT Sep 8, 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