- Temperature
- Feels like
- Rain
- Wind
- Sea water
- Waves
- Updated
Sea water: 18.2°C, practically unchanged all week
Waves: 1.9m
At 18.2 °C the water in Cascais is fresh. Fine for a dip, but the first minute bites.
Sunrise: 07:14 · Sunset: 19:54 · Day length: 12h 40m
| Day | Sea water | Waves |
|---|---|---|
| Wednesday 09/09 | 18.2 °C | 1.9 m |
| Thursday 10/09 | 17.5 °C | 1.9 m |
| Friday 11/09 | 17.1 °C | 1.6 m |
| Saturday 12/09 | 17.4 °C | 1.1 m |
| Sunday 13/09 | 17.2 °C | 1.4 m |
| Monday 14/09 | 17.7 °C | 1.4 m |
| Tuesday 15/09 | 17.8 °C | 1.3 m |
| Month | Average water |
|---|---|
| January | 15.6 °C |
| February | 14.9 °C |
| March | 14.9 °C |
| April | 15.8 °C |
| May | 16.2 °C |
| June | 17.5 °C |
| July | 17.1 °C |
| August | 16.6 °C |
| September | 16.8 °C |
| October | 18.2 °C |
| November | 17.9 °C |
| December | 16.2 °C |
Monthly averages for 2022–2025.
This page shows the water temperature at Cascais today and over the next seven days, so you can pick the best beach day before you go.
Sea temperature moves much more slowly than air temperature. A hot afternoon does not warm the ocean, and a windy day can cool it fast. Checking the water itself is the only reliable way to know what to expect.
Cascais lies where the Tagus estuary meets the open Atlantic, just west of Lisbon. Summer upwelling keeps the water noticeably cooler than in the Algarve, and it can drop several degrees in a couple of days when the northerly wind blows, so the daily reading matters here.
The water is warmest in October, averaging 18.2 °C, and coldest in February at 14.9 °C. On the west coast the peak arrives late, in early autumn, because summer upwelling keeps pulling cold deep water to the surface.
The ocean gains and loses heat far more slowly than land, so it runs months behind the seasons. On top of that, the summer northerly wind pushes surface water offshore and draws cold deep water up in its place, which is why a heatwave on land so often coincides with a colder sea.
At Guincho, windsurfers and kitesurfers fly on nortada afternoons, with international competitions every summer. The bay beaches keep a tame sea for swimming, and surf and sailing schools cover the gentle start.