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.
|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.
|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.
|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.
|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 Time||1 am||4 am||7 am||10 am||1 pm||4 pm||7 pm||10 pm||Humidity %||78||79||78||70||68||68||72||76|
|9.2 mph||August wind speed average||14.8 kph|
August is the least windy month for Key West.
|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.