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

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Current conditions at

The Florida Keys - Marathon International Airport (KMTH)

Lat: 24.73°NLon: 81.05°WElev: 13ft.

Fair

81°F

27°C

Humidity 91%
Wind Speed NE 5 mph
Barometer 30.01 in (1016.1 mb)
Dewpoint 78°F (26°C)
Visibility 10.00 mi
Heat Index89°F (32°C)
Last update 18 Sep 7:53 am EDT
Extended Forecast for

Marathon FL

  • Today

    Today: Showers likely and possibly a thunderstorm. Partly sunny, with a high near 89. East wind around 5 mph. Chance of precipitation is 60%.

    High: 89 °F

    Showers
    Likely

  • Tonight

    Tonight: A chance of showers and thunderstorms. Partly cloudy, with a low around 80. Northeast wind 5 to 10 mph. Chance of precipitation is 50%.

    Low: 80 °F

    Chance
    T-storms

  • Saturday

    Saturday: Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. East wind around 5 mph. Chance of precipitation is 60%.

    High: 88 °F

    Showers
    Likely

  • Saturday Night

    Saturday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 80. East wind 5 to 10 mph. Chance of precipitation is 50%.

    Low: 80 °F

    Chance
    T-storms

  • Sunday

    Sunday: Showers likely and possibly a thunderstorm. Mostly sunny, with a high near 88. South wind around 5 mph. Chance of precipitation is 60%.

    High: 88 °F

    Showers
    Likely

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 80. Chance of precipitation is 50%.

    Low: 80 °F

    Chance
    T-storms

  • Monday

    Monday: Showers likely and possibly a thunderstorm. Partly sunny, with a high near 89. Chance of precipitation is 60%.

    High: 89 °F

    Showers
    Likely

  • Monday Night

    Monday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 70%.

    Low: 81 °F

    Showers
    Likely

  • Tuesday

    Tuesday: Showers and thunderstorms likely. Partly sunny, with a high near 89. Chance of precipitation is 70%.

    High: 89 °F

    T-storms
    Likely

Detailed Forecast

Today
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 89. East wind around 5 mph. Chance of precipitation is 60%.
Tonight
A chance of showers and thunderstorms. Partly cloudy, with a low around 80. Northeast wind 5 to 10 mph. Chance of precipitation is 50%.
Saturday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. East wind around 5 mph. Chance of precipitation is 60%.
Saturday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 80. East wind 5 to 10 mph. Chance of precipitation is 50%.
Sunday
Showers likely and possibly a thunderstorm. Mostly sunny, with a high near 88. South wind around 5 mph. Chance of precipitation is 60%.
Sunday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 80. Chance of precipitation is 50%.
Monday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 89. Chance of precipitation is 60%.
Monday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 70%.
Tuesday
Showers and thunderstorms likely. Partly sunny, with a high near 89. Chance of precipitation is 70%.
Tuesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 80. Chance of precipitation is 70%.
Wednesday
Showers and possibly a thunderstorm. High near 89. Chance of precipitation is 80%.
Wednesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 80. Chance of precipitation is 70%.
Thursday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. Chance of precipitation is 70%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Marathon FL
 24.72°N 81.07°W (Elev. 7 ft)
Last Update:
8:15 am EDT Sep 18, 2026
Forecast Valid:
8am EDT Sep 18, 2026-6pm EDT Sep 24, 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