September weather forecast
Lisbon, Portugal

The beautiful hillside city of Lisbon in Portugal, with a high, far view of the Sao Jorge Castle
The beautiful hillside city of Lisbon in Portugal, with a high, far view of the Sao Jorge Castle

Weather in September

September, the first month of the autumn, in Lisbon, is also a moderately hot month, with average temperature fluctuating between 26.5°C (79.7°F) and 17.6°C (63.7°F).

Temperature

In September, the average high-temperature is essentially the same as in August - a still moderately hot 26.5°C (79.7°F). In Lisbon, the average low-temperature is 17.6°C (63.7°F).

Rainfall

In Lisbon, in September, during 6 rainfall days, 32.9mm (1.3") of precipitation is typically accumulated. In Lisbon, during the entire year, the rain falls for 112 days and collects up to 774mm (30.47") of precipitation.

Sea temperature

The month with the warmest seawater in Lisbon is September, with an average sea temperature of 19.9°C (67.8°F).
Note: Swimming in 19.9°C (67.8°F) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 21°C (69.8°F).

Daylight

In September, the average length of the day is 12.4h.

Sunshine

In September, the average sunshine in Lisbon is 9h.

UV index

In Lisbon, the average daily maximum UV index is 6. A UV Index of 6 to 7 symbolizes a high threat to health from the exposure to the Sun's UV radiation for ordinary individuals.
Note: The average daily UV index of 6 in September transform into the following instructions:
Take precautions against overexposure. Protection against sun damage is needed. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

How many days does it rain in September in Lisbon?

In Lisbon, in September, during 6 rainfall days, 32.9mm (1.3") of precipitation is typically accumulated.

What month is the sea warmest in Lisbon?

With an average sea temperature of 19.9°C (67.8°F), September is the month with the warmest seawater.

What is the sea water temperature in September in Lisbon?

In Lisbon, Portugal, in September, the average water temperature is 19.9°C (67.8°F). For most, swimming in 19.9°C (67.8°F) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 21°C (69.8°F) to 15°C (59°F).

What is the average length of the day in September in Lisbon?

In September, the average length of the day in Lisbon, Portugal, is 12.4h.

How many hours of sunshine does Lisbon have in September?

In September, the average sunshine in Lisbon, Portugal, is 9h.

What is the UV index intensity in September in Lisbon?

In September, the average daily maximum UV index in Lisbon, Portugal, is 6. A UV Index estimate of 6 to 7 represents a high health risk from unsafe exposure to the Sun's UV rays.

Average temperature in September
Lisbon, Portugal

Average temperature in September - Lisbon, Portugal
  • Average high temperature in September: 26.5°C

The warmest month (with the highest average high temperature) is August (28.3°C).
The month with the lowest average high temperature is January (14.8°C).

  • Average low temperature in September: 17.6°C

The month with the highest average low temperature is August (18.6°C).
The coldest month (with the lowest average low temperature) is January (8.3°C).

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Average rainfall in September
Lisbon, Portugal

Average rainfall in September - Lisbon, Portugal
  • Average rainfall in September: 32.9mm

The wettest month (with the highest rainfall) is November (127.6mm).
The driest month (with the least rainfall) is July (4.2mm).

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Average rainfall days in September
Lisbon, Portugal

Average rainfall days in September - Lisbon, Portugal
  • Average rainfall days in September: 6 days

Months with the highest number of rainy days are January, February and December (14 days).
Months with the least rainy days are July and August (2 days).

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Average sea temperature in September
Lisbon, Portugal

Average sea temperature in September - Lisbon, Portugal
  • Average sea temperature in September: 19.9°C

The best month for swimming (with the highest average sea temperature) is September (19.9°C).
The coldest month (with the lowest average sea temperature) is March (15.1°C).

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Average daylight in September /
Average sunshine in September
Lisbon, Portugal

Average daylight in September / Average sunshine in September - Lisbon, Portugal
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.5h).

  • Average sunshine in September: 9h

Months with the most sunshine are July and August (Average sunshine: 11h).
Months with the least sunshine are January, February, November and December (Average sunshine: 5).

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Average UV index in September
Lisbon, Portugal

Average UV index in September - Lisbon, Portugal
  • Average UV index in September: 6

Months with the highest UV index are June and July (UV index 9).
Months with the lowest UV index are January and December (UV index 2).

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