Weather in Key West: Climate, Seasons, and Average Monthly Temperature

Buoy monument marking southern most point in United States at Key West, Florida
Getty Images/Danita Delimont

If you would like to ​​escape the cold north during the winter or are looking for a domestic vacation to a tropical paradise in the summer, there is no better place to be than Key West, Florida, the southernmost city in the continental U.S.

Annually, Key West has an overall average high temperature of 83 degrees Fahrenheit (28 degrees Celsius) and an average low of 73 (23), making it an ideal destination year-round. With average daytime temperatures in the mid-70s during December, January, and February, the winter weather is definitely a big draw, and during June, July, and August, water temperatures in the Gulf of Mexico and the Atlantic Ocean that surround Key West climb up to the upper 80s, making it the perfect destination for a relaxing vacation to the beach.

No matter what time of year you plan to visit Key West, you should make sure you're aware of what weather you'll encounter so you can plan what to pack and what to do on your trip.

Fast Climate Facts

  • Hottest Month: August, 90 degrees Fahrenheit (32 degrees Fahrenheit)
  • Coldest Month: January, 70 degrees Fahrenheit (21 degrees Celsius)
  • Wettest Month: September, 5.45 inches
  • Best Month for Swimming: August, when the Gulf of Mexico is 87 degrees Fahrenheit

Hurricane Season

The Florida Keys, including Key West, have largely escaped effects from hurricanes in the last decade. However, the Atlantic Hurricane Season—which affects Florida and the rest of the southeastern United States—runs from June 1 through November 30 each year. If you are visiting during hurricane season, it is important to note that Key West will require a mandatory evacuation if a storm is headed toward the city.

Winter in Key West

Late December to mid-March is perhaps the best time to visit Key West due to the low amount of rainfall (and absence of hurricanes) and high temperatures the area experiences throughout the winter season. As an added bonus, the pleasant weather means Key West's Master Chef's Classic can be held outdoors so you can sample some of the best cuisines right by the sea.

What to Pack: Although winter is the driest season, it's also the coldest. With overnight lows of 65 degrees Fahrenheit (18 degrees Celsius) in January and February, you may want to pack a light jacket or sweater if you're planning some evening adventures in Key West. During the day, though, you'll still be able to wear shorts, light T-shirts, and sandals, and will likely need sunscreen and a beach blanket if you plan to soak up some winter sun.

Average Air and Water Temperatures by Month:

  • December: 77 F (25 C) / 65 F (18 C); Gulf temperature 72 F (22 C), Atlantic temperature 74 F (23 C)
  • January: 75 F (24 C) / 65 F (18 C); Gulf temperature 69 F (20 C), Atlantic temperature 71 F (22 C)
  • February: 71 F (22 C) / 66 F (19 C); Gulf temperature 70 F (21 C), Atlantic temperature 71 F (22 C)

Spring in Key West

As temperatures start to rise in the rest of the United States, fewer tourists crowd the beaches in Key West from March through May each year, making it a great time to cash in on some great vacation packages from area resorts. Additionally, the water and weather are great throughout the season, with an average air temperature of 77 degrees Fahrenheit (25 degrees Celsius) and average ocean and gulf temperatures hovering above 70 degrees Fahrenheit (21 degrees Celsius) from March through May.

What to Pack: Since nighttime lows only dip down to 69 degrees Fahrenheit (20 degrees Celsius) at their lowest, you might not need to worry about bringing a sweater anymore, but you might still consider a long-sleeved shirt for evenings. While March and April are slightly drier, May and June both see plenty of rain, so you'll also want to pack an umbrella and raincoat and be sure to check the weather before you go out during late spring.

Average Air and Water Temperatures by Month:

  • March: 79 F (26 C) / 69 F (20 C); Gulf temperature 75 F (24 C), Atlantic temperature 73 F (23 C)
  • April: 82 F (28 C) / 72 F (22 C); Gulf temperature 78 F (26 C), Atlantic temperature 77 F (25 C)
  • May: 85 F (29 C) / 76 F (24 C); Gulf temperature 82 F (28 C), Atlantic temperature 80 F (27 C)

Summer in Key West

Due to the Atlantic Hurricane Season, summer is the rainiest time of year in Key West, but it's also the hottest—and the busiest when it comes to tourist crowds and annual events. While you can expect an average of 17 days of rain per month throughout the summer, if you happen to find a sunny day on your trip, you'll need to prepare for some sweltering temperatures and some pretty harsh humidity.

What to Pack: Leave the long sleeves at home since highs and lows throughout the season never really dip below the upper 70s. Pack as light as possible, bringing linens and other breathable clothing for knocking around the beach and resort, but also be sure to bring some business casual wear if you're planning to visit any of the more upscale establishments in Key West—even though it's hot, many of these venues still have strict dress codes in the summer.

Average Air and Water Temperatures by Month:

  • June: 88 F (31 C) / 79 F (26 C); Gulf temperature 85 F (29 C), Atlantic temperature 83 F (28 C)
  • July: 89 F / 80 F (27 C); Gulf temperature 87 F (31 C), Atlantic temperature 85 F (29 C)
  • August: 90 F (32 C) / 79 F (26 C); Gulf temperature 87 F (31 C), Atlantic temperature 86 F (30 C)

Fall in Key West

As the hurricane season winds down in October and November, festive events fill the streets of Key West ranging from a city-wide Fantasy Festival that takes over the island to the beginning of Key West Holiday Fest during Thanksgiving.

What to Pack: As the nighttime temperatures start to drop and since hurricanes and tropical storms are often expected throughout much of the season, you'll want to come prepared for anything if you visit from late September to late November this year. Be sure to bring long and short-sleeved shirts, a light jacket, a raincoat, an umbrella, and beach-appropriate attire so you're ready for whatever weather comes to Key West this season.

Average Air and Water Temperatures by Month:

  • September: 88 F (31 C) / 79 F (26 C); Gulf temperature 86 F (20 C), Atlantic temperature 85 F (29 C)
  • October: 85 F (29 C) / 76 F (24 C); Gulf temperature 82 F (28 C), Atlantic temperature 82 F (28 C)
  • November: 81 F (27 C) / 72 F (22 C); Gulf temperature 76 F (24 C), Atlantic temperature 82 F (28 C)

Average Monthly Temperature, Rainfall, and Daylight Hours

  • January: 70 F (21 C), 2.22 inches, 8 hours
  • February: 72 F (22 C), 1.51 inches, 9 hours
  • March: 74 F (23 C), 1.86 inches, 9 hours
  • April: 77 F (25 C), 2.06 inches, 10 hours
  • May: 81 F (27 C), 3.48 inches, 11 hours
  • June: 85 F (29 C), 4.57 inches, 10 hours
  • July: 85 F (29 C), 3.27 inches, 11 hours
  • August: 85 F (29 C), 5.4 inches, 10 hours
  • September: 85 F (29 C), 5.45 inches, 9 hours
  • October: 81 F (27 C), 4.34 inches, 8 hours
  • November: 77 F (25 C), 2.64 inches, 9 hours
  • December: 72 F (22 C), 2.14 inches, 8 hours
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