September weather forecast
Treasure Island, FL

September brings a slight relief from the summer highs, as temperatures fall between 77.9°F (25.5°C) and 86.5°F (30.3°C). The skies are less sunny compared to August, indicating the gradual transition towards the fall season. Rainfall also witnesses a decrease, with about 17.5 days of precipitation in the month, giving way to clearer skies. The sea cools down gracefully, still maintaining an appealing temperature. A hike in the wind speed to about 7.9mph (12.7km/h) makes evenings quite pleasant.

Temperature

The transition into September shows a subtle variation to a still tropical 86.5°F (30.3°C) from August's 87.8°F (31°C) in the average high-temperature. During the nights of September, Treasure Island maintains an almost steady temperature with an average low of 77.9°F (25.5°C).

Heat index

The heat index in September is calculated to be a very hot 98.6°F (37°C). Greater safety measures are needed, risk of heat exhaustion and heat cramps is high. Continuous activity might trigger heatstroke.
Metrics for the heat index primarily focus on shaded spots and light wind conditions. If exposed to direct sunlight, the heat index could climb by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'real feel' or 'apparent temperature', stands as a testimony to how temperature and humidity combine to impact our sense of warmth. Depending on the activity and the individual's heat perception, which may vary due to factors including wind, clothing, and metabolic variations, this effect remains subjective. Be mindful that being in direct sunlight might mean feeling hotter, with the heat index rising by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for children. Children frequently underestimate the necessity to rest and hydrate. Thirst is a late sign of dehydration - thus, it is vital to stay hydrated, particularly during lengthy physical exercises.
To cool down, the human body relies on perspiration, a process where excessive heat is eliminated as sweat evaporates. When air moisture content is high, the cooling process through evaporation is not as efficient, leading to an ineffective body cooling process and a feeling of overheating. Excessive heat gain, when not shed effectively by the body, can result in increasing body temperatures and related hazards.

Humidity

The average relative humidity in September is 74%.

Rainfall

In September, the rain falls for 17.5 days. Throughout September, 1.02" (26mm) of precipitation is accumulated. In Treasure Island, during the entire year, the rain falls for 122.3 days and collects up to 9.45" (240mm) of precipitation.

Ocean temperature

In September, the average ocean temperature is 84.7°F (29.3°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

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 7:51 pm. On the last day of September, sunrise is at 7:23 am and sunset at 7:17 pm EDT.

Sunshine

The average sunshine in September is 9.2h.

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 risk from unsafe exposure to UV radiation for average individuals.
Note: The maximum UV index of 7 during September translates into these guidelines:
Undertake protective measures and comply with sun safety rules. Shielding against skin and eye damage is essential. Limit your exposure to the sun's UV radiation, which is strongest between 10 a.m. and 4 p.m., and note that parasols or canopies may not provide full sun protection. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Watch out! Sand and water enhance the UV exposure you receive.