Click on a day for an hourly weather forecast
The temperatures in Cascais in September are comfortable with low of 18°C and and high up to 26°C.
You can expect a few rainy days in Cascais during September, but usually the weather is comfortable in September.
Our weather forecast can give you a great sense of what weather to expect in Cascais in September 2025.
If you’re planning to visit Cascais in the near future, we highly recommend that you review the 14 day weather forecast for Cascais before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 15° / 10° | 3 | 28 | 0 | 35 mm | Good | Cascais in January |
| February | 16° / 10° | 3 | 26 | 0 | 34 mm | Good | Cascais in February |
| March | 18° / 11° | 3 | 28 | 0 | 39 mm | Good | Cascais in March |
| April | 19° / 13° | 2 | 28 | 0 | 34 mm | Good | Cascais in April |
| May | 22° / 15° | 1 | 30 | 0 | 23 mm | Good | Cascais in May |
| June | 24° / 17° | 0 | 30 | 0 | 9 mm | Perfect | Cascais in June |
| July | 26° / 18° | 0 | 31 | 0 | 2 mm | Perfect | Cascais in July |
| August | 28° / 18° | 0 | 31 | 0 | 3 mm | Perfect | Cascais in August |
| September | 26° / 18° | 1 | 29 | 0 | 19 mm | Perfect | Cascais in September |
| October | 23° / 17° | 2 | 29 | 0 | 42 mm | Perfect | Cascais in October |
| November | 18° / 13° | 3 | 27 | 0 | 50 mm | Good | Cascais in November |
| December | 16° / 11° | 3 | 28 | 0 | 44 mm | Good | Cascais in December |