Portugal Temperature Map

Viana do Castelo sea water temperature

Sea water: 20.6°C, practically unchanged all week

Waves: 0.9m

At 20.6 °C the water in Viana do Castelo is pleasant for swimming by Atlantic standards.

Sunrise: 06:24 · Sunset: 20:58 · Day length: 14h 34m

Sea temperature in Viana do Castelo for the next 7 days

Day Sea water Waves
Monday 27/07 20.6 °C 0.9 m
Tuesday 28/07 20.6 °C 0.7 m
Wednesday 29/07 20.2 °C 0.5 m
Thursday 30/07 19.8 °C 0.6 m
Friday 31/07 19.9 °C 0.7 m
Saturday 01/08 20.1 °C 0.5 m
Sunday 02/08 20.4 °C 0.6 m

Average sea temperature in Viana do Castelo, month by month

Month Average water
January 13.6 °C
February 13.5 °C
March 14.1 °C
April 15.8 °C
May 15.9 °C
June 17.6 °C
July 16.8 °C
August 16.4 °C
September 16.7 °C
October 18.0 °C
November 16.5 °C
December 14.5 °C

Monthly averages for 2022–2025.

This page shows the water temperature at Viana do Castelo 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.

Viana do Castelo sits on the Minho coast, with Cabedelo beach across the mouth of the Lima river. Reliable wind makes it a kitesurfing and windsurfing destination, and the sea is among the coldest in the country, typically 15 to 17 °C in summer.

Frequently asked questions

When is the sea warmest in Viana do Castelo?

The water is warmest in October, averaging 18.0 °C, and coldest in February at 13.5 °C. This is Portugal's coldest water: upwelling is at its most persistent here and holds the warming back even at the height of summer.

Why is the water colder than the air in Viana do Castelo?

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.

What can you do in the sea in Viana do Castelo?

Cabedelo is the stage: kitesurfing and windsurfing on nortada afternoons, surf schools in the tamer morning sea. From the top of Santa Luzia you can see the whole coast, and the Lima river adds rowing and sailing on sheltered water.

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