The sea, month by month

What is the sea temperature on the Costa Brava month by month?

Warmest in August at about 25°C and coldest in February at about 13°C, per seatemperature.info's 10-year averages for Sant Feliu de Guíxols.

The curve lags the air by a month or two. The sea warms slowly through May, jumps in June, peaks in August and still holds summer warmth in September. October sits near where June does. From December to April the average stays at or below 15°C.

Averages hide a spread. The same page gives a June range from about 16°C to almost 26°C over the decade, so a cool June week and a warm one can feel like different seas. Check the day's reading on seatemperature.info before you go if the water matters to you.

How warm is the sea on the Costa Brava now?

About 18°C. Seatemperature.info gave 18.1°C (64.6°F) at Sant Feliu de Guíxols on 13 November 2026, a little above the November average of about 17.2°C.

That is fresh, not cold. With the sea still above 15°C, a wetsuit top makes a two-hour paddle comfortable, and several kayak centres lend one on cooler days. If you snorkel, you will feel it after ten minutes.

For the air and the forecast on the beach itself, AEMET, Spain's state weather agency, publishes a beach forecast for named beaches, with the morning and afternoon outlook.

How hot did the sea get in 2025 and 2026?

Hotter than ever recorded. June and July 2025 set all-time highs off Catalonia, and the summer of 2026 was the warmest on record, 2.3°C above the 1982 to 2022 average.

Catalan News reported on 14 September 2025, using ICATMAR data, that the sea off Catalonia averaged 24.1°C in June 2025 and 26.73°C in July, both all-time highs, with the summer about 2°C above the 1982 to 2022 average. At L'Estartit, the observer Josep Pascual measured 26.8°C on 18 July 2025, above the previous record of 26°C from 23 July 2023, per Catalan News on 24 October 2025. Early October 2025 ran 1.8°C above the 1998 to 2022 average there.

Then 2026 went further. Catalan News reported on 9 September 2026 that the June to August average on the Catalan coast reached 26.1°C, the highest since at least 1982, and that the State Ports buoy off Begur averaged a record 24.1°C for the summer. Warm for swimming, clearly. It also means the monthly averages above, taken over ten years, may run a little low for a recent summer.

What is the best month to kayak on the Costa Brava?

September, for us: the sea is still about 23.5°C and the tours were still running all month in 2026. June is the close second if you prefer the long days.

June to October is the warm window, with average water above 20°C in every month. August is the warmest. September keeps nearly all of that warmth; one September reviewer on the sea caves tour describes exploring caves, snorkeling and jumping off rocks. David (Sep 2026): “Really great activity. [...] We recommend this activity without hesitation!”

Wind matters as much as water. The Visit Begur climate page names three: the Garbí, which blows especially in summer, the Llevant, which dominates on the coast in spring and autumn, and the Tramuntana, a strong north wind, mostly in winter. The Rats Penats listing sets out early because the sea is typically calm in the morning. For autumn paddling, see our autumn post.

When do you need a wetsuit for kayaking on the Costa Brava?

Below about 15°C, take one without question; in spring and late autumn most people want one anyway. Several tours lend them on cooler days.

The RNLI, the UK's lifeboat charity, defines anything below 15°C as cold water that “can seriously affect your breathing and movement”. On the Costa Brava that covers the average sea from about December to April. On a sit-on-top you sit in the splash, and the snorkel stop means getting in.

The listings take care of it. These lend a wetsuit or neoprene:

The Costa Brava's most booked kayak tour: sea caves and rock passages off S'Agaró, a snorkel stop, and a wetsuit on the coldest days.

★ 4.7 · 2 hours · from $38

Explore the sea caves tour from S'Agaró → Tour details

Is the water warm enough to snorkel?

From June to October, yes for most people. Snorkel gear comes with most tours here; on the Medes Islands kayak tour, bring your own.

The snorkel stop is where the warm months pay off: fish, sea urchins and anemones over the rocks, per the Sant Feliu listing, and with luck a starfish or an octopus. Marcel (Aug 2026), on the Sant Feliu tour: “With very beautiful landscapes and a background with lots of fish and even starfish.”

The sea state decides whether the stop happens, in any month. If you feel the cold, ask for the wetsuit at the start rather than halfway. More on kit in our guide to what to wear, and on cold water and capsizing in our safety guide.

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