Cascais weather in September 2026

Q: How hot is it in Cascais in September?

Daytime temperatures usually reach 27°C in Cascais in September with low heat and humidity, falling to 17°C at night.

Q: How sunny is it in Cascais in September?

There are normally 9 hours of bright sunshine each day in Cascais in September - that's 68% of daylight hours.

Q: How warm is the sea around Cascais in September?

The average sea temperature around Cascais in September is 19°C.

Q: Does it rain in Cascais in September?

There are usually 6 days with some rain in Cascais in September and the average monthly rainfall is 26mm.

Expect daytime maximum temperatures of 26°C in Cascais, Portugal in September based on long-term weather averages. There are 8 hours of sunshine per day on average.

26
26°C max day temperature
8
8 hours of sunshine per day
6
6 days with some rainfall
17
17°C min night temperature
12
12 hours of daylight per day
0
No heat & humidity
31
31 mm of monthly rainfall
6
6 (High) UV index
19
19°C sea temperature

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The September weather guide for Portugal (Cascais) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm) | Imperial (°F / inches)