United States · Florida Keys
Key West
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Climate · monthly averages
Sea temperature by month
30-year averages (1996–2025). Min/Max are typical daily lows and highs, not record extremes.
68°F
72°F
75°F
79°F
82°F
86°F
90°F
93°F
January
73.8°F(72°F–76°F)
February
73.9°F(72°F–76°F)
March
75.5°F(73°F–78°F)
April
77.8°F(76°F–80°F)
May
81.0°F(79°F–83°F)
June
84.1°F(83°F–86°F)
July
85.8°F(85°F–87°F)
August
86.5°F(85°F–88°F)
September
85.6°F(84°F–87°F)
October
82.9°F(82°F–84°F)
November
79.0°F(77°F–81°F)
December
76.2°F(75°F–78°F)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MinMin °F | 7272.0 | 7272.0 | 7372.6 | 7675.9 | 7979.0 | 8382.8 | 8584.6 | 8585.4 | 8484.5 | 8281.7 | 7777.2 | 7574.7 |
| AvgAvg °F | 7473.8 | 7473.9 | 7575.5 | 7877.8 | 8181.0 | 8484.1 | 8685.8 | 8786.5 | 8685.6 | 8382.9 | 7979.0 | 7676.2 |
| MaxMax °F | 7675.7 | 7676.1 | 7877.7 | 8080.1 | 8382.9 | 8685.7 | 8787.1 | 8887.9 | 8787.0 | 8484.2 | 8180.8 | 7877.9 |
Warmest in August (86.5°F). Coldest in January (73.8°F). Comfortable for swimming year-round.
About Key West
Key West sits at the southern tip of the Florida Keys, last island on the Overseas Highway and southernmost city in the contiguous United States. Its calling card is the Southernmost Point Buoy, a painted concrete cone at South and Whitehead Streets announcing 90 miles to Cuba. Smathers Beach runs the longest strand of imported sand along the Atlantic shore, while Fort Zachary Taylor offers deeper, snorkel-friendly water inside the historic state park. The sea holds 29-31 °C from July through September, with Key West International airport 10 minutes away.