September weather forecast
North Key Largo, FL

September, the first month of the autumn in North Key Largo, is still a tropical month, with an average temperature fluctuating between 80.4°F (26.9°C) and 87.3°F (30.7°C).

Temperature

The shift into September finds North Key Largo at an average high-temperature of a still hot 87.3°F (30.7°C), closely comparable to August's conditions. During the September nights, North Key Largo's temperature maintains an average close to the daytime highs, settling at a warm 80.4°F (26.9°C).

Heat index

During September, the heat index is computed to be a sweltering 98.6°F (37°C). Incorporate special precautions, risk of heat exhaustion and heat cramps is substantial. Sustained activity could cause heatstroke.
Understand that the heat index values take into account shaded locations and mild winds. 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 'feels like' or 'real feel', is an amalgamation of air temperature and humidity to express the equivalent perceived temperature. This effect is personal, shaped by the individual's physical activity and heat sensitivity, influenced by factors including wind, clothing, and metabolic variances. 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 highly critical for babies and toddlers. Kids are generally in more danger than adults because they perspire less. Their large skin surface area compared to their small bodies and the excessive heat due to their actions raises their risk.
The human body normally cools itself by perspiration, as evaporated sweat carries heat away from the body. Under conditions of increased relative humidity, the evaporation rate lessens, causing the body to retain more heat than under less humid conditions. As the body gains more heat than it can dissipate, there's a risk of increasing temperatures and resultant overheating.

Humidity

In North Key Largo, the average relative humidity in September is 72%.

Rainfall

In North Key Largo, in September, during 26.5 rainfall days, 5.71" (145mm) of precipitation is typically accumulated. Throughout the year, there are 225.9 rainfall days, and 40.91" (1039mm) of precipitation is accumulated.

Ocean temperature

In North Key Largo, in September, the average water temperature is 85.6°F (29.8°C).
Note: Swimming, diving, and other water activities in temperatures ranging from 77°F (25°C) to 84.2°F (29°C) are highly enjoyable and provide prolonged comfort without unease.

Daylight

In September, the average length of the day in North Key Largo is 12h and 17min.
On the first day of September in North Key Largo, Florida, sunrise is at 7:02 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 7:08 pm EDT.

Sunshine

In North Key Largo, the average sunshine in September is 8.9h.

UV index

The months with the highest UV index are April through September, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health risk from exposure to the Sun's UV radiation for average individuals.
Note: A typical high UV index of 7 in September suggests the following recommendations:
Resist overexposure. Safeguarding from solar damage is indispensable. Avoid direct Sun exposure and seek shade from 10 a.m. to 4 p.m., the period of highest UV radiation. Remember, however, that not all shade structures offer full protection. Stay sun-safe with clothing that is both closely woven and worn loosely. Be careful! The Sun's UV radiation is accentuated by reflecting off sand and water.