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Note: Observation, Forecast, and Warning data are generally available upon request via your local weather office. However, data obtained through a Weather Forecast Office is UNOFFICIAL data and generally not acceptable for legal use. The data posted on this Florida Keys Climatology website is unofficial station data. For official climate records, please visit the National Centers for Environmental Information.


Climate Normals
(Long-term Average)
Record Data Observation Site



The Florida Keys are a chain of islands that swing in a southwesterly arc from the southeast coast of the Florida peninsula, with the island of Key West being located near the western end this chain. Due to the nearness of the Gulf Stream in the Straits of Florida, and the tempering effects of the Gulf of Mexico, the Florida Keys have a notably mild, tropical-maritime climate.
Diurnal temperature variations throughout the year range about 10 degrees. Winter cold fronts tend to be modified by the warm water as they move in from the north, keeping monthly average temperatures typically only 15 degrees lower in the winter than during the summer. There is still no record of frost, ice, sleet, or snow in Key West, but ice has been reported in the Upper Keys.

December through April, referred to as the dry season, receives just shy of 25 percent of the annual rainfall, usually ahead of cold fronts. June through October is considered the wet season, receiving approximately 65 percent of the yearly total in showers and thunderstorms. May and November are typically seen as transition months between seasons. Easterly waves during this season occasionally bring excessive rainfall, while infrequent hurricanes may be accompanied by unusually heavy amounts.



Normal Temperature & Precipitation Data
(1991-2020 Normals)


Florida Keys Annual Normals

Temperature (°F)
Temperature (°F)
Temperature (°F)
Key West 83.7 78.9 74.0 40.44
Marathon 84.5 78.8 73.1 39.72



 Seasonal - Key West & Marathon (PDF Format)
Key West Seasonal Normals Graphic Marathon Seasonal Normals Graphic



Monthly - ASOS & COOP Sites from Dry Tortugas to John Pennekamp (PDF Format)
Key West Monthly Normals Graphic Marathon Monthly Normals Graphic



Daily - Key West (PDF Format) Daily - Marathon (PDF Format)
Key West Daily Normals Graphic Marathon Daily Normals Graphic




Record Temperature & Precipitation Tables
( PDF Format )

1871/1872 - Present

1950/1951 - Present

1948/1949 - 2009


Top 5 Rankings in Past 30 Years
( Key West Only, 1981-2010 - PDF Format )

Top 10 Rankings On Record
( Key West Only, 1871-Present - PDF Format )


Key West Weather Office & Climate Observation History

Key West is one of the longer climate record sites in the United States, with continuous records dating back to 1871Shown below are a couple of maps depicting the office/climate observation sites over the years, as well as a table with more detailed information on these locations. While the weather office moved to the Key West International Airport in July of 1957, the climate record site did not transition to this location until March  1st, 1958. It has remained at the airport ever since, though with several localized moves.

Image of Climate Observation Site History


Additional Local Climate Links


Historical Data from around the Florida Keys

Key West Heat Index and Dew Point Climatology
Heat Index and Dew Point Climatology Methodology
Courtesy of Brian McNoldy (University of Miami)

What are Heating / Cooling Degree Days?

Wind Frequency Plots for Key West