Marathon, Florida Weather

The average monthly temperature and rainfall in Marathon

Dolphin Encounter in Marathon, FL
••• Becky DiCello of Parker, Colorado greets a resident dolphin at the Dolphin Research Center in Marathon, FL. © Photographer, Debbie Speak/Getty Images

Environment-friendly attractions are what draws visitors to Marathon, Florida. Located midway between Key Largo and Key West in the Florida Keys, Marathon is known for its boating and fishing culture that includes deep-sea, reef, and flats fishing. Visitors to Marathon can explore all types of marine life in as well, from stingrays to dolphins to sea turtles, both in nature or one of the island's many marine life reserves.

Of course, with an overall average high temperature of 84° and an average low of 66°, it might just be the weather that makes visitors want to stay forever.

Packing for a vacation in Marthon is pretty simple, though, since majority of the attractions are outdoors. Bring your bathing suit to swim with the dolphins, relax on the beach, take up a new Watersport, or just get your tan on. Of course, you'll also need resort casual clothing for dining out, or strolling the streets during the night and evening hours. The dress code in most of the Florida Keys is cool, casual and comfortable — island style, so nothing too fancy is necessary.  

On average, Marathon's warmest month is July while January is the average coolest month. The highest recorded temperature in Marathon was a sweltering 104° in 1998 and the lowest recorded temperature was a very chilly 25° in 1989. The maximum average rainfall usually falls in August.

The Florida Keys are not often affected by hurricanes, although were hit pretty hard during 2017's Hurricane Irma. Storm season is unpredictable so there is always a possibility of getting hit during the Atlantic hurricane season which runs from June 1 through November 30.

Average temperatures, rainfall and sea temperatures for Marathon:

January

  • Average High: 75° F
  • Average Low: 64° F
  • Average Precipitation: 1.61 inches
  • Average Sea Temperature: 72.4° F

February

  • Average High Temperature: 77° F
  • Average Low Temperature: 66° F
  • Average Precipitation: 2.2 inches
  • Average Sea Temperature: 72.2° F

March

  • Average High Temperature: 79° F
  • Average Low Temperature: 69° F
  • Average Precipitation: 2.4 inches
  • Average Sea Temperature: 74.1° F

April

  • Average High Temperature: 83° F
  • Average Low Temperature: 72° F
  • Average Precipitation: 2.36 inches
  • Average Sea Temperature: 78.1° F

May

  • Average High Temperature: 87° F
  • Average Low Temperature: 76° F
  • Average Precipitation: 3.35 inches
  • Average Sea Temperature: 80.9° F

June

  • Average High Temperature: 90° F
  • Average Low Temperature: 79° F
  • Average Precipitation: 5.59 inches
  • Average Sea Temperature: 83.4° F

July

  • Average High Temperature: 91° F
  • Average Low Temperature: 79° F
  • Average Precipitation: 4.29 inches
  • Average Sea Temperature: 85.4° F

August

  • Average High Temperature: 91° F
  • Average Low Temperature: 79° F
  • Average Precipitation: 7.01 inches
  • Average Sea Temperature: 86.8° F

September

  • Average High Temperature: 89° F
  • Average Low Temperature: 78° F
  • Average Precipitation: 7.72 inches
  • Average Sea Temperature: 85.4° F

October

  • Average High Temperature: 85° F
  • Average Low Temperature: 76° F
  • Average Precipitation: 4.76 inches
  • Average Sea Temperature: 82.8° F

November

  • Average High Temperature: 80° F
  • Average Low Temperature: 71° F
  • Average Precipitation: 2.83 inches
  • Average Sea Temperature: 78.6° F

December

  • Average High Temperature: 77° F
  • Average Low Temperature: 67° F
  • Average Precipitation: 2.01 inches
  • Average Sea Temperature: 75.2° F

Visit weather.com for current weather conditions, 5- or 10-day forecast and more.

If you're planning a Florida vacation or getaway, find out more about weather, events and crowd levels from our month-by-month guides.