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

Dangerous Heat and Possible Flooding

Dangerous heat will persist across the Southwest U.S. through Saturday with daytime highs of 110-115°F. Extreme Heat Warnings remain in effect. Dangerous heat will build across the southern Plains again beginning this weekend. Heavy to excessive rain over the Carolinas Friday may lead to isolated areas of flash flooding. Read More >

Hazardous Weather Conditions

Current conditions at

The Florida Keys - Marathon International Airport (KMTH)

Lat: 24.73°NLon: 81.05°WElev: 13ft.

Fair

87°F

31°C

Humidity 72%
Wind Speed Vrbl 7 mph
Barometer 30.04 in (1017.1 mb)
Dewpoint 77°F (25°C)
Visibility 10.00 mi
Heat Index99°F (37°C)
Last update 28 Aug 1:53 pm EDT
Extended Forecast for

Long Key FL

  • This Afternoon

    This Afternoon: A chance of showers and thunderstorms. Sunny, with a high near 89. East wind around 5 mph. Chance of precipitation is 40%.

    High: 89 °F

    Chance
    T-storms

  • Tonight

    Tonight: A slight chance of showers and thunderstorms. Mostly clear, with a low around 83. East wind 5 to 10 mph. Chance of precipitation is 20%.

    Low: 83 °F

    Slight Chance
    T-storms

  • Saturday

    Saturday: A chance of showers and thunderstorms. Sunny, with a high near 89. East wind 5 to 10 mph. Chance of precipitation is 40%.

    High: 89 °F

    Chance
    T-storms

  • Saturday Night

    Saturday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 84. East wind around 10 mph. Chance of precipitation is 40%.

    Low: 84 °F

    Chance
    T-storms

  • Sunday

    Sunday: A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Southeast wind around 10 mph. Chance of precipitation is 50%.

    High: 88 °F

    Chance
    T-storms

  • Sunday Night

    Sunday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 82. Chance of precipitation is 30%.

    Low: 82 °F

    Chance
    T-storms

  • Monday

    Monday: A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Chance of precipitation is 40%.

    High: 88 °F

    Chance
    T-storms

  • Monday Night

    Monday Night: A chance of showers and thunderstorms. Partly cloudy, with a low around 84. Chance of precipitation is 50%.

    Low: 84 °F

    Chance
    T-storms

  • Tuesday

    Tuesday: Showers and thunderstorms likely. Mostly sunny, with a high near 88. Chance of precipitation is 60%.

    High: 88 °F

    T-storms
    Likely

Detailed Forecast

This Afternoon
A chance of showers and thunderstorms. Sunny, with a high near 89. East wind around 5 mph. Chance of precipitation is 40%.
Tonight
A slight chance of showers and thunderstorms. Mostly clear, with a low around 83. East wind 5 to 10 mph. Chance of precipitation is 20%.
Saturday
A chance of showers and thunderstorms. Sunny, with a high near 89. East wind 5 to 10 mph. Chance of precipitation is 40%.
Saturday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 84. East wind around 10 mph. Chance of precipitation is 40%.
Sunday
A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Southeast wind around 10 mph. Chance of precipitation is 50%.
Sunday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 82. Chance of precipitation is 30%.
Monday
A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Chance of precipitation is 40%.
Monday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 84. Chance of precipitation is 50%.
Tuesday
Showers and thunderstorms likely. Mostly sunny, with a high near 88. Chance of precipitation is 60%.
Tuesday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 84. Chance of precipitation is 50%.
Wednesday
A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Chance of precipitation is 50%.
Wednesday Night
A chance of showers and thunderstorms. Partly cloudy, with a low around 83. Chance of precipitation is 50%.
Thursday
A chance of showers and thunderstorms. Mostly sunny, with a high near 88. Chance of precipitation is 50%.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Long Key FL
 24.83°N 80.81°W (Elev. 0 ft)
Last Update:
1:15 pm EDT Aug 28, 2026
Forecast Valid:
1pm EDT Aug 28, 2026-6pm EDT Sep 3, 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