September weather forecast
Port-au-Prince, Haiti

The transition from summer to autumn sees a drop in temperatures with the maximum temperature decreasing to 29.8°C (85.6°F) and minimum to 21.3°C (70.3°F). However, the quantity of rainfall increases significantly, making September the month with the highest rainfall at 135mm (5.31") for the entire year in Port-au-Prince. Despite this, the sea remains perfectly warm at 29.8°C (85.6°F), perfect for snorkeling or diving. The city still enjoys 12.2 hours of daylight, providing plenty of time for sightseeing or exploring, albeit with an umbrella in hand. The wind speed also witnesses a swift drop to 6.5km/h (4mph), making the weather much more stagnant.

Temperature

Port-au-Prince signifies an average high-temperature of a moderately hot 29.8°C (85.6°F) in September, closely mirroring the 30.9°C (87.6°F) of August. The average low-temperature of 21.3°C (70.3°F) is witnessed in Port-au-Prince during September.

Heat index

September's mean heat index is estimated at a torrid 36°C (96.8°F). Implement heightened safety measures - risk of heat exhaustion and heat cramps is increased. Prolonged activity may result in heatstroke.
Understand that the heat index values take into account shaded locations and mild winds. Exposure to the direct sun could elevate the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature' or 'apparent temperature', integrates the air's temperature and its humidity to showcase the felt temperature by people. The impression of weather on a person can be swayed by additional aspects, including metabolic variations, pregnancy, and activity levels. In direct sunlight, the heat's impact can be heightened, potentially leading to an increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values hold great significance to children. Youngsters frequently overlook the need for breaks and fluid intake. Thirst is an advanced sign of dehydration - thereby highlighting the importance of keeping hydrated, particularly during long physical activities.
For the human body, perspiration is the go-to method to regulate temperature, using sweat's evaporation to dissipate warmth. An upsurge in relative humidity affects normal body cooling mechanisms by slowing evaporation, hence reducing the rate at which the body cools and intensifying the perception of heat. With body temperatures on the rise, inefficient heat shedding can lead to dehydration and its associated complications.

Humidity

In Port-au-Prince, the average relative humidity in September is 77%.

Rainfall

In Port-au-Prince, during September, the rain falls for 22.4 days and regularly aggregates up to 135mm (5.31") of precipitation. In Port-au-Prince, during the entire year, the rain falls for 227.4 days and collects up to 904mm (35.59") of precipitation.

Sea temperature

The month with the warmest seawater is September, with an average sea temperature of 29.8°C (85.6°F).
Note: Water temperatures from 25°C (77°F) to 29°C (84.2°F) make swimming, diving, and similar activities highly pleasurable and enjoyable for long periods without discomfort.

Daylight

In September, the average length of the day in Port-au-Prince is 12h and 14min.
On the first day of September, sunrise is at 06:34 and sunset at 19:03. On the last day of the month, sunrise is at 06:39 and sunset at 18:38 EDT.

Sunshine

In Port-au-Prince, the average sunshine in September is 9.6h.

UV index

The months with the lowest UV index are January through May, July through December, with an average maximum UV index of 6. A UV Index reading of 6 to 7 represents a high threat to health from exposure to the Sun's UV radiation for the ordinary person.
Note: In September, the maximum UV index of 6 translates into these guidelines:
Take precautions against overexposure. Protection against sun damage is needed. Between 10 a.m. and 4 p.m., the Sun emits the most powerful UV radiation. Limit direct exposure to the Sun during these hours. Protect your eyes, ears, face, and neck from the Sun by wearing a wide-brimmed hat. Alert! The Sun's UV rays are heightened by the reflection of sand and water.