September weather forecast
Jacksonville, FL

Water geysers at the fountain of Jacksonville in Florida, USA, with the cityscape
Water geysers at the fountain of Jacksonville in Florida, USA, with the cityscape

Weather in September

September, the first month of the autumn in Jacksonville, is still a tropical month, with an average temperature ranging between min 73.8°F (23.2°C) and max 86.9°F (30.5°C).

Temperature

In Jacksonville, the average high-temperature in September is essentially the same as in August - a still hot 86.9°F (30.5°C). In Jacksonville, Florida, the average low-temperature is 73.8°F (23.2°C).

Heat index

In September, the average heat index is appraised at a torrid 100.4°F (38°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. With exposure to direct sunlight, the heat index may be increased by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like', 'apparent temperature', 'felt air temperature', or 'real feel', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like metabolic differences, clothing, differences in body mass, height, and shape, 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 especially crucial for babies and toddlers. Young children are generally more endangered than adults, as they usually less sweat. And also, due to larger skin surface relative to their small bodies and higher heat production as a result of their activity.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. Under high air temperature and humidity (high heat index) conditions, perspiration is limited, and the perception of heat is increased. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 99.5°F (37.5°C) to 100.9°F (38.3°C), thermal conditions are potentially life-threatening.

Humidity

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

Rainfall

In Jacksonville, in September, during 18.5 rainfall days, 2.48" (63mm) of precipitation is typically accumulated. Throughout the year, in Jacksonville, there are 172.6 rainfall days, and 25.35" (644mm) of precipitation is accumulated.

Snowfall

In Jacksonville, snow does not fall in January through November.

Ocean temperature

In September, the average ocean temperature is 82.9°F (28.3°C).
Note: Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

Daylight

In Jacksonville, Florida, the average length of the day in September is 12h and 20min.
On the first day of the month, sunrise is at 7:03 am and sunset at 7:49 pm. On the last day of September, in Jacksonville, sunrise is at 7:19 am and sunset at 7:13 pm EDT.

Sunshine

In Jacksonville, the average sunshine in September is 8.5h.

UV index

In September, the average daily maximum UV index in Jacksonville is 6. A UV Index reading of 6 to 7 represents a high health risk from exposure to the Sun's UV rays for average individuals.
Note: The daily maximum UV index of 6 in September interpret into the following advice:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. 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. 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 temperature in September in Jacksonville?

In Jacksonville, Florida, in September, the average high-temperature is 86.9°F (30.5°C), and the average low-temperature is 73.8°F (23.2°C). The average heat index (a.k.a. 'real feel', 'feels like'), which combines relative humidity and air temperature, in September is appraised at 100.4°F (38°C).

What is the average humidity in September in Jacksonville?

In September, the average relative humidity in Jacksonville is 75%.

How many days does it rain in September in Jacksonville?

In Jacksonville, during September, the rain falls for 18.5 days and regularly aggregates up to 2.48" (63mm) of precipitation.

When it does not snow in Jacksonville?

In Jacksonville, Florida, snow does not fall in January through November.

What is the water temperature in September in Jacksonville?

In Jacksonville, Florida, the average seawater temperature in September is 82.9°F (28.3°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.

How many hours of daylight does Jacksonville have in September?

The average day length in September in Jacksonville, Florida, is 12h and 20min.

When is the sunrise / sunset in September in Jacksonville?

In September, on the first day of the month, sunrise is at 7:03 am and sunset at 7:49 pm. On the last day of the month, in Jacksonville, Florida, sunrise is at 7:19 am and sunset at 7:13 pm EDT.

How many hours of sunshine does Jacksonville have in September?

The average sunshine duration in September in Jacksonville is 8.5h.

What is the UV index reading in September in Jacksonville?

In Jacksonville, the average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Jacksonville, FL

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

The warmest months (with the highest average high temperature) are July and August (91.4°F).
The month with the lowest average high temperature is January (63.1°F).

  • Average low temperature in September: 73.8°F

The month with the highest average low temperature is August (76.6°F).
The coldest month (with the lowest average low temperature) is January (47.8°F).

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Average pressure in September
Jacksonville, FL

Average pressure in September - Jacksonville, FL
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The months with the lowest atmospheric pressure are June, August and September (29.98"Hg).

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Average wind speed in September
Jacksonville, FL

Average wind speed in September - Jacksonville, FL
  • Average wind speed in September: 5.7mph

The windiest month (with the highest average wind speed) is April (6.8mph).
The calmest months (with the lowest average wind speed) are July and August (5.2mph).

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Average humidity in September
Jacksonville, FL

Average humidity in September - Jacksonville, FL
  • Average humidity in September: 75%

The month with the highest relative humidity is December (76%).
The month with the lowest relative humidity is March (69%).

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Average rainfall in September
Jacksonville, FL

Average rainfall in September - Jacksonville, FL
  • Average rainfall in September: 2.48"

The wettest month (with the highest rainfall) is August (3.66").
The driest month (with the least rainfall) is January (1.1").

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Average rainfall days in September
Jacksonville, FL

Average rainfall days in September - Jacksonville, FL
  • Average rainfall days in September: 18.5 days

The month with the highest number of rainy days is August (23.3 days).
The month with the least rainy days is November (9 days).

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Average snowfall days in September
Jacksonville, FL

Average snowfall days in September - Jacksonville, FL
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is December (0.1 days).
The months with the least snowfall days are January, February, March, April, May, June, July, August, September, October and November (0 days).

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Average sea temperature in September
Jacksonville, FL

Average sea temperature in September - Jacksonville, FL
  • Average sea temperature in September: 82.9°F

The best month for swimming (with the highest average sea temperature) is August (83.5°F).
The coldest month (with the lowest average sea temperature) is February (60.4°F).

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Average daylight in September /
Average sunshine in September
Jacksonville, FL

Average daylight in September / Average sunshine in September - Jacksonville, FL
  • Average daylight in September: 12h and 20min

The month with the longest days is June (Average daylight: 14h and 4min).
The month with the shortest days is December (Average daylight: 10h and 14min).

  • Average sunshine in September: 8h and 30min

The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).

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Average sunshine days in September
Jacksonville, FL

Average sunshine days in September - Jacksonville, FL
  • Average sunshine days in September: 8.7 days

The month with the most sunshine days is January (18.8 days).
The month with the least sunshine days is August (6.3 days).

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Average UV index in September
Jacksonville, FL

Average UV index in September - Jacksonville, FL
  • Average UV index in September: 6

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

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Average cloud cover in September
Jacksonville, FL

Average cloud cover in September - Jacksonville, FL
  • Average cloud cover in September: 32

The month with the most cloud cover is December (Cloud cover 39).
The month with the least cloud cover is May (Cloud cover 27).

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Average visibility in September
Jacksonville, FL

Average visibility in September - Jacksonville, 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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