August 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
August is a hot summer month with average high temperatures of 90°F (32.2°C). It is rainy as thunderstorms are frequent during the summer. The sun is unrelenting with the ultraviolet index at 11, and the daylight stretches to 14 hours.
Tourists desert Key West with peak summer in August, but any remaining travelers get great deals on everything. There are a low number of tour operators during the off-season, but there are no restrictions on renting boats and exploring the surroundings.
Average temperature in August - Key West, FL
  • Average high temperature in August: 89.4°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 August: 79.6°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 August - Key West, FL
  • Average humidity in August: 73.4%

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 August - Key West, FL
  • Average rainfall in August: 4.9"

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 August - Key West, FL
  • Average rainfall days in August: 14.2 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 August - Key West, FL
  • Average sea temperature in August: 86.9°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 August / Average sunshine in August - Key West, FL
  • Average daylight in August: 13h

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 August: 9.9h

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 August - Key West, FL
  • Average UV index in August: 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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