September weather forecast
Porto Santo Island, Portugal

Heading into September, Porto Santo Island begins its transition from the hot summer temperatures to the cooler autumn season. The weather remains pleasantly warm, but with a tangible lessening of the intense summer heat that characterized the previous months. Light breezes start sweeping across the island, ushering in the autumnal change. Nonetheless, September still experiences warm sea temperatures at 23.4°C (74.1°F). This month records an average rainfall of 13mm (0.51") over six days, indicating the initiation of the wet season after a substantially dry summer.

Temperature

Porto Santo Island experiences the peak of its temperatures in August and September, when the average high-temperatures rise to 25.1°C (77.2°F).

Humidity

In September, the average relative humidity in Porto Santo Island is 77%.

Rainfall

In September, the rain falls for 6 days. Throughout September, 13mm (0.51") of precipitation is accumulated. In Porto Santo Island, during the entire year, the rain falls for 97 days and collects up to 382mm (15.04") of precipitation.

Sea temperature

September is the month with the warmest seawater, with an average sea temperature of 23.4°C (74.1°F).
Note: Given an individual's cold sensitivity, considering factors like sunshine, wind, and air temperature, a brief swim in 23.4°C (74.1°F) water might be pleasurable. (FYI: The standard water temperature for Olympic swimming contests is 25°C (77°F) to 28°C (82.4°F).)

Daylight

In Porto Santo Island, the average length of the day in September is 12h and 22min.
On the first day of the month, sunrise is at 07:40 and sunset at 20:30. On the last day of September, in Porto Santo Island, sunrise is at 07:59 and sunset at 19:51 WEST.

Sunshine

In Porto Santo Island, the average sunshine in September is 7h.

UV index

In September, the average daily maximum UV index in Porto Santo Island is 8. A UV Index estimate of 8 to 10 represents a very high threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A typical high UV index of 8 in September suggests the following recommendations:
Precautions are essential; the risk of damage to unprotected skin and eyes is too high. Be aware that the sun's UV radiation is strongest between 10 a.m. and 4 p.m. and try to reduce direct sun exposure during this period as much as possible. On days when the sun blazes, arm yourself with sunglasses that block UVA and UVB radiation. Note! Reflective surfaces like sand and water heighten the UV radiation levels.