September weather forecast
Longboat Key, FL

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

Temperature

As Longboat Key steps into September, the average high-temperature is measured at a still tropical 86.9°F (30.5°C), displaying minor differences from August's 88.5°F (31.4°C). Longboat Key observes an average nighttime low-temperature of 77.4°F (25.2°C) during the month of September.

Heat index

September's heat index is estimated at a sweltering 100.4°F (38°C). Incorporate additional preventive steps, heat exhaustion and heat cramps are possible. Long-lasting activity may cause heatstroke.
Records show heat index calculations are tailored for shaded regions and mild winds. The heat index has the possibility to be enhanced by 15 Fahrenheit (8 Celsius) degrees when there is direct sun exposure.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. The individual's impression of temperature can be affected by numerous factors such as metabolic variations, physical exertion, and attire. 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 hold particular significance for children. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
The body's natural response to excessive warmth is perspiration, as it allows for cooling through sweat evaporation. With high air temperature and humidity (high heat index) conditions, sweat production is restricted, leading to an amplified perception of heat. Accumulating more heat than the body can dissipate leads to an uptick in body temperature, with potential heat stress consequences.

Humidity

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

Rainfall

In Longboat Key, Florida, in September, during 23.5 rainfall days, 4.61" (117mm) of precipitation is typically accumulated. Throughout the year, in Longboat Key, there are 183.1 rainfall days, and 34.92" (887mm) of precipitation is accumulated.

Ocean temperature

In Longboat Key, in September, the average water temperature is 84.7°F (29.3°C).
Note: Water temperature ranging between 77°F (25°C) and 84.2°F (29°C) is considered very warm and pleasing for everyone. It allows for enjoyable water activities over extended periods without discomfort.

Daylight

The average length of the day in September is 12h and 19min.
On the first day of September, sunrise is at 7:10 am and sunset at 7:50 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 7:17 pm EDT.

Sunshine

In September, the average sunshine is 9h.

UV index

May through September, with an average maximum UV index of 7, are months with the highest UV index in Longboat Key. A UV Index of 6 to 7 symbolizes a high threat to health from unprotected exposure to Sun's UV rays for average individuals.
Note: In September, a regular UV index of 7 translates into these guidelines:
Deflect overexposure. Sun protection is a necessity. To the best of your ability, limit your exposure to the sun between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Attention! UV strength is notably upped by the reflection of sand and water.