September weather forecast
Longboat Key, FL

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

Temperature

During September, the average high-temperature is a still tropical 86.9°F (30.5°C), maintaining a close resemblance to that of the preceding month. Longboat Key, in September, observes a steady average low-temperature of 77.4°F (25.2°C).

Heat index

Throughout September, the heat index is evaluated at a very hot 100.4°F (38°C). Ensure extra safety measures, heat exhaustion and heat cramps are likely. Continuous activity might result in heatstroke.
When assessing, remember that heat index measurements are for light winds and shaded spots. The direct sun can potentially cause the heat index to increase by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. Consider that direct sun exposure can intensify the felt heat, adding potentially 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are extremely significant for children. Youngsters are usually more at risk than adults, considering they sweat less. Additionally, their high skin surface area compared to their little bodies and their high heat production due to activity increases their risk.
The human body normally cools itself by perspiration, as evaporated sweat carries heat away from the body. Elevated relative humidity disrupts typical body cooling by reducing the evaporation rate, consequently decreasing the body's cooling rate and enhancing the feeling of heat. When body temperature rises due to excess heat gain beyond its removal capability, one might experience heat-related disorders.

Humidity

The average relative humidity in September is 75%.

Rainfall

In Longboat Key, during September, the rain falls for 23.5 days and regularly aggregates up to 4.61" (117mm) of precipitation. In Longboat Key, during the entire year, the rain falls for 183.1 days and collects up to 34.92" (887mm) of precipitation.

Ocean temperature

In Longboat Key, Florida, the average seawater temperature in September is 84.7°F (29.3°C).
Note: Engaging in water activities, such as swimming or diving, in temperatures from 77°F (25°C) to 84.2°F (29°C) is very pleasurable for extended periods, without any discomfort.

Daylight

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

Sunshine

In September, the average sunshine is 9h.

UV index

The months with the highest UV index are May through September, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV radiation for average individuals.
Note: The daily high UV index of 7 during September translates into the following recommendations:
Avert overexposure. Light-skinned people might experience burning in less than 20 minutes. Minimize exposure to direct sunlight and seek shade from 10 a.m. to 4 p.m., when UV radiation is most intense, but remember that shade structures may not offer complete protection. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Be wary! Reflections from sand and water make UV radiation more intense.