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September Weather in Porto, Spain

Last updated: August 27, 2025

In September, the average temperature in Porto, Spain hovers around 15°C (59°F), with daily variations ranging from a chilly 3°C (38°F) to a warm 30°C (86°F). Expect some rain during your stay, as the region receives about 71 mm (2.8 in) of precipitation over 9 days. Additionally, you'll find the air quite humid with an average humidity level of 77%.

September Temperature in Porto

In September in Porto, the average temperature is 15°C (59°F). The maximum can reach 30°C (86°F), while the minimum can be as low as 3°C (38°F). This climate makes Porto an ideal destination for travelers looking to enjoy mild temperatures and a range of outdoor activities.

September Weather in Porto: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Porto, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Porto, September typically has an average temperature of 15°C (59°F), with highs reaching up to 30°C (86°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec384143475459646459524341
Data source: Temperature data for Porto generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Porto

In Porto in September, the precipitation amount is 71 mm (2.8 in) spread over 9 days.

September Precipitation Trends in Porto

The chart displays monthly precipitation patterns in Porto, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Porto, September typically receives around 71 mm (2.8 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec811231351201009449347199142182
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Porto

In Porto in September, humidity is 77%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket enveloping you, making it essential to stay hydrated and choose light, breathable clothing for comfortable travel.

September Average Humidity in Porto

This chart illustrates the average monthly humidity levels in Porto, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Porto is approximately 77%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%83%83%84%84%86%78%77%82%86%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Porto

In Porto in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Porto.

Maximum UV Index Levels in Porto for September

The chart shows the monthly maximum UV Index (UVI) for Porto in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Porto typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24689111098632
Data source: Porto September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Porto Compares to Other Months

Weather in Porto varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Porto, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Porto, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather3°C (38°F)80 mm (3.2 inches)87%low
February Weather5°C (41°F)123 mm (4.8 inches)85%moderate
March Weather6°C (43°F)135 mm (5.3 inches)83%high
April Weather9°C (48°F)120 mm (4.7 inches)83%very high
May Weather12°C (54°F)100 mm (4.0 inches)84%very high
June Weather15°C (59°F)94 mm (3.7 inches)84%extreme
July Weather18°C (64°F)49 mm (1.9 inches)86%very high
August Weather18°C (64°F)34 mm (1.3 inches)78%very high
September Weather15°C (59°F)71 mm (2.8 inches)77%very high
October Weather11°C (53°F)99 mm (3.9 inches)82%high
November Weather6°C (43°F)142 mm (5.6 inches)86%moderate
December Weather5°C (41°F)182 mm (7.2 inches)87%low

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