Portugal Temperature Map

Olhão sea water temperature

Sea water: 18.1°C, practically unchanged all week

Waves: 1.0m

At 18.1 °C the water in Olhão is fresh. Fine for a dip, but the first minute bites.

Sunrise: 06:58 · Sunset: 20:06 · Day length: 13h 7m

Sea temperature in Olhão for the next 7 days

Day Sea water Waves
Friday 28/08 18.1 °C 1.0 m
Saturday 29/08 18.1 °C 0.7 m
Sunday 30/08 18.2 °C 0.7 m
Monday 31/08 17.9 °C 0.7 m
Tuesday 01/09 17.6 °C 0.7 m
Wednesday 02/09 17.8 °C 0.7 m
Thursday 03/09 18.2 °C 0.6 m

Average sea temperature in Olhão, month by month

Month Average water
January 16.5 °C
February 15.9 °C
March 15.7 °C
April 17.2 °C
May 17.1 °C
June 18.6 °C
July 18.6 °C
August 19.0 °C
September 17.6 °C
October 19.0 °C
November 18.1 °C
December 16.8 °C

Monthly averages for 2022–2025.

This page shows the water temperature at Olhão 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.

Olhão faces the Ria Formosa rather than the open sea, with the lagoon and its barrier islands between the town and the Atlantic. There is no ocean beach in Olhão itself, so bathers take the ferry across to Armona or Culatra, where the sand faces south and the water sits near 19 °C in August. The shallow channels inside the lagoon heat up much faster than that on a still day, which is why the ria feels so mild at low tide.

Frequently asked questions

When is the sea warmest in Olhão?

The water is warmest in August, averaging 19.0 °C, and coldest in March at 15.7 °C. The Algarve peaks in late summer, well after the hottest weather on land, and September usually beats June comfortably.

Why is the water colder than the air in Olhão?

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 Olhão?

Everything starts at the waterfront: ferries cross to Armona and Culatra for the beaches, and small boats run tours through the Ria Formosa channels. Kayaking and paddleboarding are the best way to reach the quiet parts of the lagoon, and the birdlife on the salt pans is worth the early start. Back on land, the covered fish market is the largest in the Algarve.

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