September weather forecast
Porto, Portugal

September in Porto presents a gentle transition into autumn. A modest decrease in maximum temperatures occurs from the peak readings in August. Yet, it's worth noting that the month receives a higher rainfall of 72mm (2.83"), heralding the onset of the wetter period. Despite this, outdoor activities can still be enjoyed due to the high number of sunshine hours. The city begins to quieten down as peak tourism season winds down.

Temperature

Porto, Portugal, registers an average high-temperature of a still warm 24.1°C (75.4°F) with the arrival of September, showing minor deviation from the preceding month. Porto's temperature in September lowers to a consistent average of 14.7°C (58.5°F) during the nights.

Rainfall

In Porto, during September, the rain falls for 8 days and regularly aggregates up to 72mm (2.83") of precipitation. Throughout the year, in Porto, there are 147 rainfall days, and 1237mm (48.7") of precipitation is accumulated.

Sea temperature

With an average sea temperature of 18.2°C (64.8°F), September is the month with the warmest seawater in Porto, Portugal.
Note: Most individuals do not find swimming at 18.2°C (64.8°F) to be enjoyable. As the water temperature declines below 21°C (69.8°F), maintaining control over one's breathing becomes harder.

Daylight

In Porto, Portugal, the average length of the day in September is 12h and 28min.
On the first day of September, sunrise is at 07:01 and sunset at 20:07. On the last day of the month, sunrise is at 07:30 and sunset at 19:17 WEST.

Sunshine

In September, the average sunshine is 7.5h.

UV index

In Porto, the average daily maximum UV index in September is 6. A UV Index estimate of 6 to 7 represents a high health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The UV index of 6 during September translates into the following guidance:
Beware of overexposure. Fair-skinned individuals risk burning in less than 20 minutes. Stay in the shade and limit sun exposure from 10 a.m. to 4 p.m., when UV radiation is most potent. Keep in mind that shade structures like parasols or canopies do not offer full protection. Always opt for UVA and UVB-resistant sunglasses on radiant days.