Thunderstorms and Heavy Rainfall in the Plains; Hazardous Heat in the South and Southeast

Severe thunderstorms will be possible across the northern/central Plains through Tuesday afternoon and from the central Plains to the Mid-Mississippi Valley Tuesday evening through Wednesday morning. Storms may produce large hail and damaging wind gusts, and heavy rainfall may lead to scattered instances of flash flooding. Meanwhile, hazardous heat persists across the South and Southeast. Read More >

Current conditions at

The Florida Keys - Marathon International Airport (KMTH)

Lat: 24.73°NLon: 81.05°WElev: 13ft.

Fair

80°F

27°C

Humidity 85%
Wind Speed Calm
Barometer 30.06 in (1018.0 mb)
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Heat Index85°F (29°C)
Last update 18 Aug 1:53 am EDT
Extended Forecast for

Marathon FL

  • Overnight

    Overnight: Mostly clear, with a low around 82. Calm wind.

    Low: 82 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 91. Calm wind becoming west around 5 mph in the afternoon.

    High: 91 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 83. Northwest wind 10 to 15 mph.

    Low: 83 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 91. North wind around 10 mph.

    High: 91 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms.  Partly cloudy, with a low around 83. Northwest wind 10 to 15 mph.  Chance of precipitation is 10%.

    Low: 83 °F

    Slight Chance
    T-storms

  • Thursday

    Thursday: A slight chance of showers and thunderstorms.  Mostly sunny, with a high near 91. Chance of precipitation is 10%.

    High: 91 °F

    Slight Chance
    T-storms

  • Thursday Night

    Thursday Night: A slight chance of showers.  Partly cloudy, with a low around 82. Chance of precipitation is 10%.

    Low: 82 °F

    Slight Chance
    Showers

  • Friday

    Friday: Sunny, with a high near 90.

    High: 90 °F

    Sunny

  • Friday Night

    Friday Night: A slight chance of showers.  Mostly clear, with a low around 82. Chance of precipitation is 10%.

    Low: 82 °F

    Slight Chance
    Showers

Detailed Forecast

Overnight
Mostly clear, with a low around 82. Calm wind.
Tuesday
Sunny, with a high near 91. Calm wind becoming west around 5 mph in the afternoon.
Tuesday Night
Partly cloudy, with a low around 83. Northwest wind 10 to 15 mph.
Wednesday
Mostly sunny, with a high near 91. North wind around 10 mph.
Wednesday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 83. Northwest wind 10 to 15 mph. Chance of precipitation is 10%.
Thursday
A slight chance of showers and thunderstorms. Mostly sunny, with a high near 91. Chance of precipitation is 10%.
Thursday Night
A slight chance of showers. Partly cloudy, with a low around 82. Chance of precipitation is 10%.
Friday
Sunny, with a high near 90.
Friday Night
A slight chance of showers. Mostly clear, with a low around 82. Chance of precipitation is 10%.
Saturday
Sunny, with a high near 90.
Saturday Night
A slight chance of showers. Mostly clear, with a low around 82. Chance of precipitation is 10%.
Sunday
Sunny, with a high near 90.
Sunday Night
A slight chance of showers and thunderstorms. Partly cloudy, with a low around 82. Chance of precipitation is 20%.
Monday
A slight chance of showers. Sunny, with a high near 91. Chance of precipitation is 10%.
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ABOUT THIS FORECAST

 
Point Forecast:
Marathon FL
 24.72°N 81.07°W (Elev. 7 ft)
1:15 am EDT Aug 18, 2026
1am EDT Aug 18, 2026-6pm EDT Aug 24, 2026
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database