Key West Weather in August

August brings some hot and stormy weather to Key West, Florida. But the storms are usually brief enough for the island to receive plenty of sunshine.

This page gives detailed information on the typical August temperature, precipitation, sun, humidity, wind and storms for Key West. The numbers here are historical averages based on climate data gathered at the Key West International Airport, located on Key West Island.

Temperature Weather iconTemperature

91 °F August average high 33 °C
81 °F August average low 27 °C

The first half of August continues the annual peak in temperature that began in late July. From August 1st to 18th the daily high averages 91 degrees Fahrenheit (33 degrees Celsius) and nighttime lows are 81 °F (27 °C).

20 days 90 °F max. or more (32 °C)
0 days 70 °F min. or less (21 °C)

Typically every August day at Key West has a temperature of at least 80 °F (27 °C). Temperatures above 100 °F (38 °C) are not expected here this month.

Rainy Weather iconRain

5.4 in total precipitation 136 mm
15 days of rain

Half the time, Key West receives 3.4 to 6.7 inches (87 to 170 mm) of rainfall in August. One in four years has drier weather, while another one in four is wetter.

Sunny Weather iconSun

76 % sunshine
3 days clear skies

The sun's rays reach the ground in Key West during 76 percent of daylight hours on average in August, for a total of 306 hours in the month. Typically on 3 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in August at Key West lasts for 12 hours and 57 minutes a day on average. The longest day of the month is the 1st with 13 hours and 15 minutes of daylight. By the end of the month, the days have shortened to 12:38 from sunrise to sunset. These durations can vary by a minute or two from year to year.

Humid Weather iconHumidity

73 % August average humidity

The relative humidity in Key West during August usually peaks at 79 percent in the morning then drops to 68 percent by early afternoon.

Local Time1 am4 am7 am10 am1 pm4 pm7 pm10 pm
Humidity % 78 79 78 70 68 68 72 76

Windy Weather iconWind

9.2 mph August wind speed average 14.8 kph

August is the least windy month for Key West.

Stormy Weather iconStorms

3 days rainfall of 0.5 inches (13 mm) or more
15 days with thunderstorms in August
10 % chance a named storm approaches

Thunderstorms happen most frequently over Key West during August.

There's a two percent probability that a hurricane will approach within 100 miles (165 km) of Key West during August. The chance of a major hurricane (category 3 to 5) reaching the area is one percent.


The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals. The named storm probabilities come from the Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Division.

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