September weather forecast
Key Biscayne, FL

The first month of the autumn, September, is also a moderately hot month in Key Biscayne, Florida, with an average temperature ranging between min 81°F (27.2°C) and max 85.6°F (29.8°C).

Temperature

Key Biscayne notes an average high-temperature of a warm 85.6°F (29.8°C) in September, displaying minor variation from August. Nights during September maintain a steady temperature, averaging at 81°F (27.2°C).

Heat index

September's mean heat index is estimated at a sweltering 95°F (35°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
It is emphasized that the heat index's values are meant for shaded zones with mild winds. 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 'feels like', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. An individual's perception of weather can be affected by a variety of elements including metabolic differences, being pregnant, and their level of physical exertion. Should you be directly under the sun, anticipate a possible increase in the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Youngsters often neglect the necessity for rest and hydration. Thirst is a sign of advancing dehydration - thus the importance of maintaining hydration, specifically during long-lasting physical activities.
As a reaction to high temperatures, the human body begins to perspire, using the evaporation of sweat to lower its temperature. Greater relative humidity lessens the rate of evaporation, thus decreasing the body's heat dispersal, which gives rise to a sensation of overheating. With body temperatures on the rise, inefficient heat shedding can lead to dehydration and its associated complications.

Humidity

In Key Biscayne, the average relative humidity in September is 73%.

Rainfall

In September, in Key Biscayne, the rain falls for 24.5 days. Throughout September, 1.93" (49mm) of precipitation is accumulated. Throughout the year, in Key Biscayne, there are 182.7 rainfall days, and 16.38" (416mm) of precipitation is accumulated.

Ocean temperature

In Key Biscayne, the average seawater temperature in September is 85.5°F (29.7°C).
Note: For engaging in water activities including swimming and diving, temperatures from 77°F (25°C) to 84.2°F (29°C) are perceived as perfect, providing pleasure for extended durations.

Daylight

In September, the average length of the day in Key Biscayne is 12h and 17min.
On the first day of the month, sunrise is at 7:01 am and sunset at 7:39 pm. On the last day of September, sunrise is at 7:12 am and sunset at 7:08 pm EDT.

Sunshine

In Key Biscayne, the average sunshine in September is 9.1h.

UV index

The months with the highest UV index are May through October, with an average maximum UV index of 7. A UV Index estimate of 6 to 7 represents a high health vulnerability from exposure to the Sun's UV rays for average individuals.
Note: An average maximum UV index of 7 in September leads to these recommendations:
Incorporate safeguards and honour sun safety principles. Protection from skin and eye damage is obligatory. Stay out of direct sunlight between 10 a.m. and 4 p.m., when UV radiation is most intense, and remember that not all shade structures provide complete protection. Stay sun-safe with clothing that is both closely woven and worn loosely. Be vigilant! The Sun's UV rays get a boost from sand and water reflections.