September weather forecast
Lisbon, Portugal

September sees a subtle shift in weather patterns in Lisbon, marking the beginning of the cooling down process. Despite the average temperature falling to 26.5°C, the sun continues to shine bright, albeit for fewer hours. Though the city experiences marginally more rainfall than the previous month, the weather remains conducive for outdoor activities. A dip in sea temperatures may deter beach visits, but the city remains a hub of leisure and enjoyment. The UV index is dropping, indicating shorter daylight hours, but the pleasant weather ensures the tourism industry continues to thrive.

Temperature

September's advent in Lisbon notes a subtle adjustment in average high-temperature to a still warm 26.5°C from August. Lisbon in September experiences a low-temperature average of 17.6°C.

Rainfall

In Lisbon, in September, during 6 rainfall days, 33mm of precipitation is typically accumulated. Throughout the year, there are 112 rainfall days, and 774mm of precipitation is accumulated.

Sea temperature

With an average sea temperature of 19.9°C, September is the month with the warmest seawater.
Note: Most individuals do not find swimming at 19.9°C to be enjoyable. As the water temperature declines below 21°C, maintaining control over one's breathing becomes harder.

Daylight

In September, the average length of the day in Lisbon is 12h and 26min.
On the first day of September in Lisbon, sunrise is at 07:05 and sunset at 20:07. On the last day of the month, sunrise is at 07:31 and sunset at 19:21 WEST.

Sunshine

The average sunshine in September is 9h.

UV index

The average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV radiation for the average person.
Note: In September, a regular UV index of 6 translates into these guidelines:
Implement precautions and maintain sun safety methods. Avoidance of sunburn is demanded. 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. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage.