September weather forecast
Naples, FL

September signifies a gradual decline in the intensity of summer in Naples. There's a slight fall in day temperatures and a lesser increase in rainfall from a high of 4.29" (109mm) in August to 2.4" (61mm). Nevertheless, The sea temperature remains high, allowing for swimming and other water-based activities. In addition, daylight hours start to decrease steadily indicating the nearing autumnal equinox. To summarise, September is a transitional month where summer starts fading out.

Temperature

With the advent of September, Naples's high-temperatures adjust to a still hot 87.1°F (30.6°C), closely aligning with the preceding month. Naples records a slight downturn in temperature to an average of 78.4°F (25.8°C) during September nights.

Heat index

The heat index in September is appraised at a torrid 100.4°F (38°C). More protective measures are required - heat exhaustion and heat cramps are likely. Heatstroke may follow lengthy activity.
Note that heat index values are valued for light wind and location in the shade. Direct sunshine exposure could raise heat index values by as much as 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', integrates the air's temperature and its humidity to showcase the felt temperature by people. A person's impression of weather can be shaped by many aspects, among them metabolic variations, pregnancy, and levels of physical activity. Take note that direct exposure to the sun can increase the felt temperature, possibly adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values are especially crucial for babies and toddlers. Young individuals are generally in more danger than adults due to their lower capacity to sweat. Moreover, their large skin surface in relation to their small bodies and the increased heat generation from their activities makes them more vulnerable.
The physiological response of the human body to excess warmth is to perspire, thereby cooling itself through sweat evaporation. Relative humidity in excess curtails evaporation, therefore reducing heat dissipation from the body, leading to feelings of excess heat. Heat-related challenges, like dehydration, can be anticipated when body heat isn't managed effectively.

Humidity

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

Rainfall

In September, the rain falls for 21.5 days. Throughout September, 2.4" (61mm) of precipitation is accumulated. Throughout the year, there are 162.1 rainfall days, and 21.69" (551mm) of precipitation is accumulated.

Ocean temperature

In Naples, Florida, the average seawater temperature in September is 85.6°F (29.8°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

The average length of the day in September is 12h and 18min.
On the first day of the month, sunrise is at 7:07 am and sunset at 7:46 pm. On the last day of September, sunrise is at 7:19 am and sunset at 7:14 pm EDT.

Sunshine

In Naples, the average sunshine in September is 9.2h.

UV index

May through September, with an average maximum UV index of 7, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high threat to health from unsafe exposure to UV radiation for ordinary individuals.
Note: The maximum UV index of 7 during September translates into these guidelines:
Refrain from overexposure. Fair-skinned individuals could burn in under 20 minutes. From 10 a.m. to 4 p.m., when UV radiation is at its strongest, limit direct exposure to the Sun and note that shade structures may not provide full sun protection. Employ a wide-brim hat for potent defense against up to 50% of UV rays. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.