May weather forecast and climate
Key West, FL

A beach pier in Key West, Florida, with palm trees in the background
A beach pier in Key West, Florida, with palm trees in the background
Sunny May is basked in the brilliant daily sunshine of 11 hours with light rain up to 7 days during the month. Average lows and highs are steady between 75°F (23.9°C) to 85°F (29.4°C), as the days are noticeably warm.
Early morning is the perfect time for a bike or moped ride for people with a zeal to explore Key West in its natural surroundings. Avoid the mid-day sun and take precautions to counter the ultraviolet index of the sun at a dangerous 11. Take advantage of the low crowds on the beach and lower hotel rates during May.
Average temperature in May - Key West, FL
  • Average high temperature in May: 85°F

The warmest month (with the highest average high temperature) is August (89.4°F).
The month with the lowest average high temperature is January (74.3°F).

  • Average low temperature in May: 75.7°F

The month with the highest average low temperature is July (79.8°F).
The coldest month (with the lowest average low temperature) is January (64.2°F).

Average humidity in May - Key West, FL
  • Average humidity in May: 71.8%

The month with the highest relative humidity is December (76.2%).
The month with the lowest relative humidity is April (70.1%).

Average rainfall in May - Key West, FL
  • Average rainfall in May: 4.2"

The wettest month (with the highest rainfall) is September (6.5").
The driest month (with the lowest rainfall) is March (1.6").

Average rainfall days in May - Key West, FL
  • Average rainfall days in May: 7.2 days

The month with the highest number of rainy days is September (16.2 days).
The month with the lowest number of rainy days is April (4.5 days).

Average sea temperature in May - Key West, FL
  • Average sea temperature in May: 80.7°F

The best month for swimming (with the highest average sea temperature) is August (86.9°F).
Coldest months (with the lowest average sea temperature) are January and February (71.2°F).

Average daylight in May / Average sunshine in May - Key West, FL
  • Average daylight in May: 13.3h

The month with the longest days is June (Average daylight: 13.6h).
The month with shortest days is December (Average daylight: 10.6h).

  • Average sunshine in May: 11h

The month with most sunshine is May (Average sunshine: 11h).
The month with least sunshine is December (Average sunshine: 7.6h).

Average UV index in May - Key West, FL
  • Average UV index in May: 11

Months with the highest UV index are April, May, June, July and August (UV index 11).
Months with the lowest UV index are January and December (UV index 6).

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