August weather forecast
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

Weather in August

August, the last month of the summer in Key West, is another warm month, with an average temperature fluctuating between 85.3°F (29.6°C) and 82.9°F (28.3°C).

Temperature

August is the warmest month, with an average high-temperature of 85.3°F (29.6°C) and an average low-temperature of 82.9°F (28.3°C).

Heat index

In August, the average heat index is appraised at a hot 95°F (35°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature', 'real feel', 'feels like', or 'felt air temperature', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (pregnancy, clothing, differences in body mass, height, and shape). Bear in mind that direct sunshine exposure increases weather impact, and may raise heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

The months with the lowest humidity are July through September, with an average relative humidity of 74%.

Rainfall

In August, in Key West, the rain falls for 23.1 days. Throughout August, 4.33" (110mm) of precipitation is accumulated. Throughout the year, in Key West, there are 199.2 rainfall days, and 31.61" (803mm) of precipitation is accumulated.

Ocean temperature

With an average ocean temperature of 86.9°F (30.5°C), August is the month with the warmest seawater in Key West.
Note: For swimming, other intense water activities, temperature above 86°F (30°C) is arguably unpleasant, as the water cooling effect is missing.

Daylight

The average length of the day in August is 12h and 58min.
On the first day of the month, sunrise is at 6:55 am and sunset at 8:11 pm. On the last day of August, in Key West, sunrise is at 7:08 am and sunset at 7:46 pm EDT.

Sunshine

In August, the average sunshine is 9.7h.

UV index

The months with the highest UV index are April through October, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health vulnerability from exposure to the Sun's UV rays for the average person.
Note: In August, the average maximum UV index of 7 translate into the following recommendations:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.
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FAQ

What is the warmest month in Key West?

The warmest month in Key West, Florida, is August, with an average high-temperature of 85.3°F (29.6°C) and an average low-temperature of 82.9°F (28.3°C).

What is the temperature in August in Key West?

In Key West, in August, the average high-temperature is 85.3°F (29.6°C), and the average low-temperature is 82.9°F (28.3°C). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which factors the actual air temperature with the relative humidity, in August is appraised at 95°F (35°C).

What is the least humid month in Key West?

July through September, with an average relative humidity of 74%, are the least humid months.

What is the average humidity in August in Key West?

In Key West, Florida, the average relative humidity in August is 74%.

How many days does it rain in August in Key West?

In August, the rain falls for 23.1 days. Throughout August, 4.33" (110mm) of precipitation is accumulated.

What is the month with the warmest ocean in Key West?

August is the month with the warmest seawater in Key West, Florida, with an average ocean temperature of 86.9°F (30.5°C).

What is the ocean temperature in August in Key West?

In Key West, Florida, the average seawater temperature in August is 86.9°F (30.5°C). For swimming, other intense water activities, temperature above 86°F (30°C) is arguably unpleasant, as the water cooling effect is missing.

What is the average length of the day in August in Key West?

In August, the average day length in Key West, Florida, is 12h and 58min.

When are sunrise and sunset in August in Key West?

In August, on the first day of the month, sunrise is at 6:55 am and sunset at 8:11 pm. On the last day of the month, in Key West, sunrise is at 7:08 am and sunset at 7:46 pm EDT.

How many hours of sunshine does Key West have in August?

The average sunshine duration in August is 9.7h.

What is the month with the highest UV index in Key West?

The months with the highest UV index in Key West, Florida, are April through October, with an average maximum UV index of 7.

What is the UV index reading in August in Key West?

In Key West, Florida, the average daily maximum UV index in August is 7. A UV Index of 6 to 7 symbolizes a high health threat from unsafe exposure to Sun's UV rays.

Average temperature in August
Key West, FL

Average temperature in August - Key West, FL
  • Average high temperature in August: 85.3°F

The warmest month (with the highest average high temperature) is August (85.3°F).
The month with the lowest average high temperature is January (72.7°F).

  • Average low temperature in August: 82.9°F

The month with the highest average low temperature is August (82.9°F).
The coldest month (with the lowest average low temperature) is January (68.5°F).

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Average pressure in August
Key West, FL

Average pressure in August - Key West, FL
  • Average pressure in August: 29.97"

The month with the highest atmospheric pressure is January (30.09").
The months with the lowest atmospheric pressure are September and October (29.93").

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Average wind speed in August
Key West, FL

Average wind speed in August - Key West, FL
  • Average wind speed in August: 10.1mph

The windiest months (with the highest average wind speed) are January and November (14.4mph).
The calmest month (with the lowest average wind speed) is July (9.5mph).

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Average humidity in August
Key West, FL

Average humidity in August - Key West, FL
  • Average humidity in August: 74%

The month with the highest relative humidity is February (78%).
The months with the lowest relative humidity are July, August and September (74%).

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Average rainfall in August
Key West, FL

Average rainfall in August - Key West, FL
  • Average rainfall in August: 4.33"

The wettest month (with the highest rainfall) is September (5.12").
The driest month (with the least rainfall) is March (0.67").

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Average rainfall days in August
Key West, FL

Average rainfall days in August - Key West, FL
  • Average rainfall days in August: 23.1 days

The months with the highest number of rainy days are August and September (23.1 days).
The month with the least rainy days is February (11 days).

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Average sea temperature in August
Key West, FL

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).
The coldest months (with the lowest average sea temperature) are January and February (71.2°F).

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Average daylight in August /
Average sunshine in August
Key West, FL

Average daylight in August / Average sunshine in August - Key West, FL
  • Average daylight in August: 12h and 58min

The month with the longest days is June (Average daylight: 13h and 38min).
The month with the shortest days is December (Average daylight: 10h and 39min).

  • Average sunshine in August: 9.7h

The month with the most sunshine is July (Average sunshine: 11h).
The month with the least sunshine is December (Average sunshine: 6.3h).

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Average sunshine days in August
Key West, FL

Average sunshine days in August - Key West, FL
  • Average sunshine days in August: 6.2 days

The month with the most sunshine days is March (17 days).
The month with the least sunshine days is September (4.5 days).

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Average UV index in August
Key West, FL

Average UV index in August - Key West, FL
  • Average UV index in August: 7

The months with the highest UV index are April, May, June, July, August, September and October (UV index 7).
The month with the lowest UV index is January (UV index 5).

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Average cloud cover in August
Key West, FL

Average cloud cover in August - Key West, FL
  • Average cloud cover in August: 28

The month with the most cloud cover is January (Cloud cover 34).
The month with the least cloud cover is April (Cloud cover 23).

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Average visibility in August
Key West, FL

Average visibility in August - Key West, FL
  • Average visibility in August: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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