Marathon Temperatures: Averages by Month





The numbers here tell you how hot and cold the weather usually is at Marathon, in the Florida Keys during each month of the year.

The average high and low temperatures are listed below monthly and annually for Boot Key and its neighbors, in both degrees Fahrenheit and Celsius.

Maximums and minimums are only part of the temperature picture. To fill in the rest, there's information on how many days a month get above or below a given temperature.

To find out how often it rises over 70, 80 or 90 °F each month in Marathon, scroll down farther. There are also monthly and yearly counts of days with cool weather.

All the numbers are averages, based on climate data gathered from 1981 to 2010.

Average Marathon temperatures
High °F Low °F   High °C Low °C
75 64 January 24 18
77 66 February 25 19
79 69 March 26 20
83 72 April 28 22
87 76 May 30 25
90 79 June 32 26
91 79 July 33 26
91 79 August 33 26
89 79 September 32 26
86 76 October 30 24
81 71 November 27 22
77 67 December 25 19
84 73 Year 29 23

Days of Hot Weather in Marathon

Winters are warm and summers hot at Marathon. From May to October, the islands average 81 days with highs in the 90s Fahrenheit. Even so, usually only once every two years does it get as hot as 100 °F (38 °C) in this stretch of Florida Keys.

Days per month in Marathon of at least 70, 80 or 90 °F
  70 °F
21 °C
80 °F
27 °C
90 °F
32 °C
January 24 8 0
February 24 9 0
March 24 16 0
April 30 25 0
May 31 31 3
June 30 30 18
July 31 31 22
August 31 31 24
September 30 30 13
October 31 29 1
November 29 18 0
December 27 11 0
Year 348 268 81

How Often Marathon Has Cool Temperatures

Cool temperatures are rare at Marathon. Just two nights a year on average have lows of 50 °F or less. Temperatures colder than 40 °F (4 °C) are not expected here.

Days per month on average in Key Largo when the minimum temperature drops to 60 or 50 °F or lower
  50 °F
10 °C
60 °F
16 °C
January 1 9
February 0 5
March 0 2
April 0 1
May 0 0
June 0 0
July 0 0
August 0 0
September 0 0
October 0 0
November 0 1
December 1 6
Year 2 24
Reference

National Climatic Data Center. NOAA's 1981-2010 Climate Normals.

Florida Temperatures
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