September weather forecast
Santo Antonio, São Tomé and Príncipe

Resuming the wet patterns, September observes a jump in rainfall to 146mm (5.75") in Santo Antonio. The month exhibits a notable difference compared to the drier August. Average daylight stays consistent, with around 12.1 hours of daylight, providing ample time for activities. Humidity levels rise marginally in response to the increased rain, a trait typical of tropical settings. Navigating through the month calls for planning around the bouts of rain and sunshine.

Temperature

Santo Antonio indicates an average high-temperature of a still moderately hot 27.4°C (81.3°F) in September, showing minor variation from August's 27.1°C (80.8°F). During the month of September, an average temperature of 21.2°C (70.2°F) is noted during the nights in Santo Antonio.

Heat index

September's mean heat index is computed to be a tropical 31°C (87.8°F). If one remains active during constant exposure, it might cause exhaustion and heat cramps.
Heat index evaluations are typically in the context of light winds and shaded environments. The heat index has the potential to rise by 15 Fahrenheit (8 Celsius) degrees with direct sunshine exposure.
Note: The heat index, also known as 'feels like' or 'felt air temperature', is a measure that combines air temperature and relative humidity into a single value that indicates how hot the weather feels. This impact is subjective, influenced by the person's physical activity and individual heat perception, affected by factors including wind, attire, and metabolic differences. Taking into account that direct sunlight can boost the heat effect, the heat index may rise by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Young people are generally more susceptible than adults because they perspire less. Furthermore, their proportionally larger skin surface to their petite bodies and the increased heat output from their actions add to the risk.

Humidity

In Santo Antonio, the average relative humidity in September is 86%.

Rainfall

In Santo Antonio, in September, it is raining for 21 days, with typically 146mm (5.75") of accumulated precipitation. In Santo Antonio, during the entire year, the rain falls for 188 days and collects up to 1872mm (73.7") of precipitation.

Sea temperature

The months with the coldest seawater are July through September, with an average sea temperature of 26°C (78.8°F).
Note: Swimming, diving, and other water activities in the temperature range of 25°C (77°F) to 29°C (84.2°F) are perceived as very enjoyable and comfortable for prolonged durations.

Daylight

In September, the average length of the day is 12h and 7min.
On the first day of September, sunrise is at 05:25 and sunset at 17:34. On the last day of the month, sunrise is at 05:17 and sunset at 17:23 GMT.

Sunshine

With an average of 2h of sunshine, September has the least sunshine of the year in Santo Antonio.

UV index

The months with the highest UV index in Santo Antonio are January through May, August through November, with an average maximum UV index of 12. A UV Index value of 11, and more, symbolizes an excessive health risk from unprotected exposure to Sun's UV rays for the average person.
Note: The maximum daily UV index of 12 in September converts into the following recommendations:
Take all required precautions, as unprotected skin and eyes can burn in minutes. Avoid direct exposure to the Sun between 10 a.m. and 4 p.m., the peak period for UV radiation, noting that objects like parasols or canopies might not offer complete sun protection. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Even on overcast days, apply and frequently reapply a sunscreen with SPF 30 or more, specifically after a swim or outdoor workout. Be vigilant! The Sun's UV rays get a boost from sand and water reflections.