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.

A Few Clouds

87°F

31°C

Humidity 72%
Wind Speed S 5 mph
Barometer 30.03 in (1016.7 mb)
Dewpoint 77°F (25°C)
Visibility 10.00 mi
Heat Index99°F (37°C)
Last update 23 Aug 8:53 am EDT
Extended Forecast for

25 Miles NNW Long Key FL

  • Today

    Today: A 30 percent chance of showers and thunderstorms, mainly after 5pm. Mostly sunny, with a high near 92. Heat index values as high as 102. Calm wind becoming south around 6 mph in the afternoon.

    High: 92 °F

    Mostly Sunny
    then Chance
    T-storms

  • Tonight

    Tonight: A chance of showers and thunderstorms before 10pm, then a slight chance of showers and thunderstorms after 5am. Partly cloudy, with a low around 77. Calm wind. Chance of precipitation is 30%.

    Low: 77 °F

    Chance
    T-storms

  • Monday

    Monday: A 20 percent chance of showers and thunderstorms, mainly between 10am and noon. Mostly sunny, with a high near 92. Heat index values as high as 101. Calm wind becoming southeast 5 to 7 mph in the afternoon.

    High: 92 °F

    Slight Chance
    T-storms then
    Mostly Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 77. Southeast wind around 5 mph becoming calm in the evening.

    Low: 77 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92. Southeast wind 3 to 8 mph.

    High: 92 °F

    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Partly cloudy, with a low around 77. East wind 3 to 6 mph. Chance of precipitation is 60%.

    Low: 77 °F

    Chance
    T-storms then
    Showers
    Likely

  • Wednesday

    Wednesday: Showers likely and possibly a thunderstorm before 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 91. Southeast wind 5 to 8 mph. Chance of precipitation is 70%.

    High: 91 °F

    Showers
    Likely

  • Wednesday Night

    Wednesday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 79. East wind 6 to 8 mph.

    Low: 79 °F

    Chance
    T-storms

  • Thursday

    Thursday: Showers likely and possibly a thunderstorm before 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 90. Southeast wind 6 to 8 mph. Chance of precipitation is 70%.

    High: 90 °F

    Showers
    Likely

Detailed Forecast

Today
A 30 percent chance of showers and thunderstorms, mainly after 5pm. Mostly sunny, with a high near 92. Heat index values as high as 102. Calm wind becoming south around 6 mph in the afternoon.
Tonight
A chance of showers and thunderstorms before 10pm, then a slight chance of showers and thunderstorms after 5am. Partly cloudy, with a low around 77. Calm wind. Chance of precipitation is 30%.
Monday
A 20 percent chance of showers and thunderstorms, mainly between 10am and noon. Mostly sunny, with a high near 92. Heat index values as high as 101. Calm wind becoming southeast 5 to 7 mph in the afternoon.
Monday Night
Mostly clear, with a low around 77. Southeast wind around 5 mph becoming calm in the evening.
Tuesday
A 50 percent chance of showers and thunderstorms. Mostly sunny, with a high near 92. Southeast wind 3 to 8 mph.
Tuesday Night
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2am. Partly cloudy, with a low around 77. East wind 3 to 6 mph. Chance of precipitation is 60%.
Wednesday
Showers likely and possibly a thunderstorm before 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 91. Southeast wind 5 to 8 mph. Chance of precipitation is 70%.
Wednesday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 79. East wind 6 to 8 mph.
Thursday
Showers likely and possibly a thunderstorm before 2pm, then a chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 90. Southeast wind 6 to 8 mph. Chance of precipitation is 70%.
Thursday Night
A 30 percent chance of showers and thunderstorms, mainly after 2am. Partly cloudy, with a low around 78.
Friday
Showers and thunderstorms likely. Mostly sunny, with a high near 90. Chance of precipitation is 60%.
Friday Night
Showers and thunderstorms likely. Partly cloudy, with a low around 78. Chance of precipitation is 60%.
Saturday
Showers and thunderstorms likely. Mostly sunny, with a high near 90. Chance of precipitation is 70%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
25 Miles NNW Long Key FL
 25.17°N 80.97°W
Last Update:
3:56 am EDT Aug 23, 2026
Forecast Valid:
9am EDT Aug 23, 2026-6pm EDT Aug 29, 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