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.

A Few Clouds

81°F

27°C

Humidity 91%
Wind Speed NE 7 mph
Barometer 29.92 in (1013.3 mb)
Dewpoint 78°F (26°C)
Visibility 10.00 mi
Heat Index89°F (32°C)
Last update 19 Sep 3:53 am EDT
Extended Forecast for

Marathon FL

  • Overnight

    Overnight: A chance of showers and thunderstorms. Mostly cloudy, with a low around 81. East wind around 5 mph. Chance of precipitation is 50%.

    Low: 81 °F

    Chance
    T-storms

  • Saturday

    Saturday: A chance of showers and thunderstorms. Partly sunny, with a high near 88. East wind around 5 mph. Chance of precipitation is 50%.

    High: 88 °F

    Chance
    T-storms

  • Saturday Night

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

    Low: 80 °F

    Chance
    T-storms

  • Sunday

    Sunday: A chance of showers and thunderstorms. Partly sunny, with a high near 87. Calm wind becoming south around 5 mph. Chance of precipitation is 50%.

    High: 87 °F

    Chance
    T-storms

  • Sunday Night

    Sunday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. South wind around 5 mph. Chance of precipitation is 70%.

    Low: 81 °F

    Showers
    Likely

  • Monday

    Monday: Showers likely and possibly a thunderstorm. Partly sunny, with a high near 87. Chance of precipitation is 70%.

    High: 87 °F

    Showers
    Likely

  • Monday Night

    Monday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 60%.

    Low: 81 °F

    Showers
    Likely

  • Tuesday

    Tuesday: Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. Chance of precipitation is 60%.

    High: 88 °F

    Showers
    Likely

  • Tuesday Night

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

    Low: 81 °F

    Showers
    Likely

Detailed Forecast

Overnight
A chance of showers and thunderstorms. Mostly cloudy, with a low around 81. East wind around 5 mph. Chance of precipitation is 50%.
Saturday
A chance of showers and thunderstorms. Partly sunny, with a high near 88. East wind around 5 mph. Chance of precipitation is 50%.
Saturday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 80. East wind around 5 mph. Chance of precipitation is 50%.
Sunday
A chance of showers and thunderstorms. Partly sunny, with a high near 87. Calm wind becoming south around 5 mph. Chance of precipitation is 50%.
Sunday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. South wind around 5 mph. Chance of precipitation is 70%.
Monday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 87. Chance of precipitation is 70%.
Monday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 60%.
Tuesday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. Chance of precipitation is 60%.
Tuesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 70%.
Wednesday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. Chance of precipitation is 70%.
Wednesday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 81. Chance of precipitation is 60%.
Thursday
Showers likely and possibly a thunderstorm. Partly sunny, with a high near 88. Chance of precipitation is 60%.
Thursday Night
A chance of showers and thunderstorms. Mostly cloudy, with a low around 81. Chance of precipitation is 50%.
Friday
Showers likely and possibly a thunderstorm. Mostly sunny, with a high near 88. Chance of precipitation is 60%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Marathon FL
 24.72°N 81.1°W (Elev. 0 ft)
Last Update:
3:15 am EDT Sep 19, 2026
Forecast Valid:
4am EDT Sep 19, 2026-6pm EDT Sep 25, 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