September weather forecast
Barthélemy, French Guiana

September in Barthélemy witnesses the least amount of rainfall in the year, down to a mere 23mm (0.91"). The drastic reduction in precipitation signifies the peak of the dry spell that began in June. Despite this, Barthélemy continues to be characterized by a warm tropical climate as temperatures, humidity, and daylight hours remain high. The UV index maintains its peak position at 7, indicative of bright and sunny days. Thus, September stands out for its particularly dry weather within the overarching tropical weather pattern in Barthélemy.

Temperature

September's onset records an average high-temperature of a still tropical 31.5°C (88.7°F), a near match to August's 30.9°C (87.6°F). Barthélemy experiences an average nighttime temperature of 24.5°C (76.1°F) in the month of September.

Heat index

For September, the heat index is evaluated at an extremely hot 41°C (105.8°F). Exercise enhanced safety steps, heat cramps and heat exhaustion are probable. Heatstroke could be a result of sustained activity.
Keep in mind the heat index values are meant for areas in shade and with light wind. Exposing to direct sunshine may enhance heat index values by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', evaluates the perceived heat by adding the effect of moisture in the air. The influence of weather is personal, differing among individuals based on variations in body mass, stature, and the degree of physical exertion. In the direct sunlight, the weather's impact can be amplified, possibly boosting the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Children often miss understanding the importance of rest and rehydration. Thirst usually appears late during dehydration - therefore, maintaining hydration, particularly during long physical activities, is essential.
As a reaction to high temperatures, the human body begins to perspire, using the evaporation of sweat to lower its temperature. A higher relative humidity affects normal body cooling by reducing the evaporation rate, subsequently lowering the rate at which the body cools and increasing the perception of heat. Overheating and potential dehydration arise when body heat gain eclipses its release capability.

Humidity

The months with the lowest humidity are September and October, with an average relative humidity of 76%.

Rainfall

September is the month with the least rainfall. Rain falls for 12.2 days and accumulates 23mm (0.91") of precipitation.

Daylight

In Barthélemy, the average length of the day in September is 12h and 8min.
On the first day of the month, sunrise is at 06:24 and sunset at 18:35. On the last day of September, in Barthélemy, sunrise is at 06:17 and sunset at 18:22 -03.

Sunshine

September has the most sunshine of the year in Barthélemy, French Guiana, with an average of 9.2h of sunshine.

UV index

The months with the highest UV index are June through November, 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 the ordinary person.
Note: A maximum daily UV index of 7 during September morphs into the following directions:
Apply measures and align with sun safety principles. Safeguarding against skin and eye injury is pivotal. During the period from 10 a.m. to 4 p.m., UV radiation is highest. Try to avoid direct sunlight during these hours. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.