SeasonMapCascais weather in September
Portugal
September in Cascais: warm, dry, with clean air — one of the best months to visit.
#2 of 12 months in Cascais · #356 of 1383 destinations to visit in September · comfort 87/100 (tier A)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Cascais in September
Other months in Cascais
Cascais's forum calls July hot and sunny but not especially humid, typically mid-20s to low-30s°C with a regular Atlantic breeze that helps take the edge off. Regulars flag the sea itself as genuinely cold year-round despite the warm air, and note evenings can turn cool enough for a light jacket even after a hot day.
Add your own note from Cascais's card on the map.
Cascais climate normals — September
| Daytime high | 25°C / 77°F | 🌤 warm |
|---|---|---|
| Nighttime low | 18°C / 65°F | |
| Feels like (high) | 26°C / 79°F | |
| Sea temperature | 18°C / 65°F | 🧊 bracing |
| Rainfall | 24 mm / 0.9 in | ☀️ dry |
| Rainy days | 3 days | |
| Humidity | 76% | 💦 very humid |
| Dew point | 15°C / 59°F | |
| Sunshine | 10.9 h/day | |
| Daylight | 12.4 h | |
| Wind | 22 km/h / 14 mph | |
| Air quality (US AQI) | 43 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Cascais in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
BusySummer holidays in Portugal, school holidays in 3 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Cascais's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Best weatherCascais's best weather comes in June, July and September — separate windows, not one continuous season.
Best weatherFair weatherToughest weather
What's on in Cascais in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
The nortada
15 Jun – 15 Sep · usuallyWind seasonRiskThe north wind gets up most summer afternoons, which is why Guincho belongs to kitesurfers and why the sheltered town beaches fill instead. Mornings are the calm half of the day.
- Season
Sea at its warmest
20 Jul – 5 Oct · usuallySea warm enoughThe Atlantic upwelling keeps this coast cold well into summer and it only comes round in August and September. The bay beaches are always a little warmer than Guincho.
Nearby, and something's on
Within 300 km of Cascais — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Cascais?
Cascais in September — FAQ
- Is September a good time to visit Cascais?
- September in Cascais: warm, dry, with clean air — one of the best months to visit. It ranks #2 of 12 months for Cascais on SeasonMap's comfort score (87/100).
- What is the weather like in Cascais in September?
- In September, Cascais averages a daily high of 25°C and a low of 18.2°C, with about 23.9 mm of rain over roughly 3.2 rainy days.
- What is the air quality in Cascais in September?
- Cascais has a mean US Air Quality Index of about 43 in September.
Other months in Cascais
Compare Cascais in September
Warmer or cooler than Cascais in September
Similar destinations in Southern Europe — September
Within 300 km: Lisbon's Grape harvest around 1 Sep – 15 Oct, and Nazaré's Romaria de Nossa Senhora da Nazare on 5–10 Sep.