September weather forecast
Siesta Key, FL

Weather in September

September, the first month of the autumn in Siesta Key, is still a tropical month, with an average temperature ranging between max 86.9°F (30.5°C) and min 77.4°F (25.2°C).

Temperature

In September, the average high-temperature is almost the same as in August - a still hot 86.9°F (30.5°C). In Siesta Key, Florida, the average low-temperature is 77.4°F (25.2°C).

Heat index

The average heat index in September is computed to be a very hot 99.9°F (37.7°C). Take extra precautions, as heat cramps and heat exhaustion are possible. Sustained activity may result in heatstroke.
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 'real feel', 'apparent temperature', 'felt air temperature', or 'feels like', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like wind, differences in body mass, height, and shape, pregnancy, and activity influence one's weather impression. 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 particularly important for children. 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.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. High relative humidity reduces the evaporation rate, resulting in a lower heat removal rate from the body, causing the perception of being overheated. When heat gain surpasses the level the body can shed, body temperature begins to increase, and consequently, overheating and dehydration can occur, with varying severity.

Humidity

The average relative humidity in September in Siesta Key is 75%.

Rainfall

In Siesta Key, in September, it is raining for 23.5 days, with typically 4.61" (117mm) of accumulated precipitation. Throughout the year, there are 183.1 rainfall days, and 34.92" (887mm) of precipitation is accumulated.

Ocean temperature

In September, the average ocean temperature is 84.7°F (29.3°C).
Note: For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

Daylight

In September, the average length of the day in Siesta Key is 12h and 19min.
On the first day of September, sunrise is at 7:09 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 7:17 pm EDT.

Sunshine

The average sunshine in September is 9h.

UV index

The months with the highest UV index in Siesta Key are May through September, with an average maximum UV index of 7. A UV Index value of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 7 in September transform into the following instructions:
Take precautions against overexposure. Protection against sun damage is needed. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.
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FAQ

What is the temperature in September in Siesta Key?

The average high-temperature, in September, in Siesta Key, Florida, is 86.9°F (30.5°C), while the average low-temperature is 77.4°F (25.2°C). The average heat index (a.k.a. 'apparent temperature', 'real feel'), which represents the influence of relative humidity on air temperature, in September is computed to be 99.9°F (37.7°C).

What is the average humidity in September in Siesta Key?

In September, the average relative humidity in Siesta Key, Florida, is 75%.

How much does it rain in Siesta Key in September?

In September, the rain falls for 23.5 days. Throughout September, 4.61" (117mm) of precipitation is accumulated.

What is the water temperature in September in Siesta Key?

In September, the average ocean temperature is 84.7°F (29.3°C). For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

What is the average length of the day in September in Siesta Key?

In September, the average day length in Siesta Key is 12h and 19min.

What time are sunrise and sunset in September in Siesta Key?

In September, on the first day of the month, sunrise is at 7:09 am and sunset at 7:50 pm. On the last day of the month, in Siesta Key, Florida, sunrise is at 7:22 am and sunset at 7:17 pm EDT.

How many hours of sunshine does Siesta Key have in September?

In September, the average sunshine duration is 9h.

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

May through September, with an average maximum UV index of 7, are months with the highest UV index in Siesta Key.

What is the UV index intensity in September in Siesta Key?

In September, the average daily maximum UV index in Siesta Key is 7. A UV Index value of 6 to 7 symbolizes a high health risk from unsafe exposure to Sun's UV rays.

Average temperature in September
Siesta Key, FL

Average temperature in September - Siesta Key, FL
  • Average high temperature in September: 86.9°F

The warmest month (with the highest average high temperature) is August (88.5°F).
The month with the lowest average high temperature is January (68.5°F).

  • Average low temperature in September: 77.4°F

The month with the highest average low temperature is August (79.7°F).
The coldest month (with the lowest average low temperature) is January (56.1°F).

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Average pressure in September
Siesta Key, FL

Average pressure in September - Siesta Key, FL
  • Average pressure in September: 29.95"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.95"Hg).

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Average wind speed in September
Siesta Key, FL

Average wind speed in September - Siesta Key, FL
  • Average wind speed in September: 7.2mph

The windiest month (with the highest average wind speed) is January (9.3mph).
The calmest month (with the lowest average wind speed) is July (6.4mph).

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Average humidity in September
Siesta Key, FL

Average humidity in September - Siesta Key, FL
  • Average humidity in September: 75%

The month with the highest relative humidity is December (76%).
The months with the lowest relative humidity are March, April and May (72%).

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Average rainfall in September
Siesta Key, FL

Average rainfall in September - Siesta Key, FL
  • Average rainfall in September: 4.61"

The wettest month (with the highest rainfall) is August (6.42").
The driest months (with the least rainfall) are February and November (1.06").

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Average rainfall days in September
Siesta Key, FL

Average rainfall days in September - Siesta Key, FL
  • Average rainfall days in September: 23.5 days

The month with the highest number of rainy days is August (26.8 days).
The months with the least rainy days are January, February and November (8.3 days).

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Average sea temperature in September
Siesta Key, FL

Average sea temperature in September - Siesta Key, FL
  • Average sea temperature in September: 84.8°F

The best month for swimming (with the highest average sea temperature) is August (86.7°F).
The coldest month (with the lowest average sea temperature) is January (64.1°F).

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Average daylight in September /
Average sunshine in September
Siesta Key, FL

Average daylight in September / Average sunshine in September - Siesta Key, FL
  • Average daylight in September: 12h and 19min

The month with the longest days is June (Average daylight: 13h and 50min).
The month with the shortest days is December (Average daylight: 10h and 28min).

  • Average sunshine in September: 9h and 0min

The month with the most sunshine is May (Average sunshine: 11h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 30min).

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Average sunshine days in September
Siesta Key, FL

Average sunshine days in September - Siesta Key, FL
  • Average sunshine days in September: 4.5 days

The month with the most sunshine days is January (21.1 days).
The month with the least sunshine days is August (2.5 days).

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Average UV index in September
Siesta Key, FL

Average UV index in September - Siesta Key, FL
  • Average UV index in September: 7

The months with the highest UV index are May, June, July, August and September (UV index 7).
The month with the lowest UV index is January (UV index 4).

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Average cloud cover in September
Siesta Key, FL

Average cloud cover in September - Siesta Key, FL
  • Average cloud cover in September: 28

The months with the most cloud cover are January and December (Cloud cover 30).
The month with the least cloud cover is May (Cloud cover 22).

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Average visibility in September
Siesta Key, FL

Average visibility in September - Siesta Key, FL
  • Average visibility in September: 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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