September weather forecast
Keystone, FL

The first month of the autumn, September, is still a hot month in Keystone, Florida, with an average temperature fluctuating between 86.7°F (30.4°C) and 77.5°F (25.3°C).

Temperature

September denotes a minimal variation in the average high-temperature to a still tropical 86.7°F (30.4°C) from August's 88.3°F (31.3°C). Keystone cools down to an average low-temperature of 77.5°F (25.3°C) throughout the month of September.

Heat index

The heat index in September is calculated to be a very hot 98.6°F (37°C). Exercise heightened safety, heat cramps and heat exhaustion are probable. Persistent activity may provoke heatstroke.
Bear in mind that the heat index values are determined for shaded areas and light breezes. Heat index values might soar by up to 15 Fahrenheit (8 Celsius) degrees with exposure to direct sunshine.
Note: The heat index, also known as 'apparent temperature' or 'real feel', is a metric representing the sensation of warmth when air temperature and moisture come together. A person's impression of weather can be shaped by many aspects, among them metabolic variations, pregnancy, and levels of physical activity. When directly under the sun, the weather's impact can intensify, possibly boosting the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for babies and toddlers. Young children typically face greater hazards than adults because they do not sweat as much. Their larger skin surface in comparison to their little bodies and the high heat production from their active nature compounds their vulnerability.
The body's self-cooling mechanism is rooted in perspiration, where evaporating sweat cools down excessive warmth. Excessive relative humidity disturbs the body's typical cooling process by reducing evaporation, leading to a decrease in body cooling rate and an increase in the sensation of warmth. Excessive heat gain, when not shed effectively by the body, can result in increasing body temperatures and related hazards.

Humidity

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

Rainfall

In Keystone, in September, during 15.7 rainfall days, 0.71" (18mm) of precipitation is typically accumulated. In Keystone, during the entire year, the rain falls for 120.5 days and collects up to 9.45" (240mm) of precipitation.

Daylight

The average length of the day in September in Keystone is 12h and 19min.
On the first day of September in Keystone, sunrise is at 7:09 am and sunset at 7:51 pm. On the last day of the month, sunrise is at 7:23 am and sunset at 7:17 pm EDT.

Sunshine

In Keystone, 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 in Keystone. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV rays for the average person.
Note: The maximum UV index of 7 during September translates into these guidelines:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. The hours from 10 a.m. to 4 p.m. have the most intense UV radiation. As much as possible, limit direct sun exposure during this period. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation.