Adriatic Sea: Swimming Season, Temperatures, Location & Size

The Adriatic Sea

Trying to figure out the best time to swim in the Adriatic Sea in Croatia? Here I’ve outlined average sea temperatures by month and season, and given some info about location so you can decide the ideal time for you!

​How long does the swimming season last in Croatia?

Pleasant swimming (in my opinion), takes place from June-September, however May and October are also candidates depending on the year! 

If September is particularly warm in a given year, then the swimming season prolongs deep into October - in 2020 for example, we visited Dubrovnik at the end of October and the sea temperature was still 22°C so it was still pleasant to swim. 
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If it’s a really warm spring, you could take a dip in May, which is when locals usually open the swimming, even if it’s cooler. 

Many of our guests ask us, when’s the best time to visit the beaches in Croatia?
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Well, the Adriatic Sea is the warmest in August, with averages generally hovering around 24 degrees celsius, but after a few days of a heat wave, sea temperatures can get to 27-28+ degrees celsius (so it feels more like a bath :) 
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If you like more refreshing temperatures for swimming, maybe you’d prefer June or September!

Here are specific temperature ranges for each month and season:

The Adriatic Sea temperature in the Winter

The Adriatic Sea  is one of the main reasons why winters here in Croatian coastal cities are quite mild. After a typically warm summer, the sea starts to cool off in October, and in the winter will drop to temperatures between 8-16 degrees celsius. It’s very unlikely that the sea would freeze. Snow is very rare along the coast, instead it’s more windy than anything. 

​Adriatic Sea Temperature in the Spring

After the winter months, the Adriatic sea starts to warm up in the spring as air temperatures start to climb. However, the water doesn’t immediately warm up, so in March and April, it’s still quite chilly, and not a lot of people start swimming yet. 

May is when things really start to warm up, and the sea temperatures typically double from the low temperatures in the winter. This is when it’s a more comfortable temperature for swimming, and people really start enjoying the sea. 

Adriatic Sea Temperature in the Summer ​

The best time to experience the sea (in my opinion), is the summer (because I like swimming in warmer water). Although the sea gets busy with tourists, there are always private coves and bays to discover, and you can always find quiet beaches to enjoy (and there are over 1200 islands and islets to explore, so just imagine all the undiscovered beauty). 
 Sea temperatures peak in July and August, where they can reach 25+ degrees celsius - very pleasant for swimming, and great temperatures for kids!

Adriatic Sea Temperature in the Fall

After the peak of summer season, air temperatures start to slowly drop, but the sea still remains quite warm and comfortable for swimming. Sometimes during the fall, the air and sea temperature actually is the same, and it’s wonderful to take a dip. We think early fall is a great time to sail as well. 
 There are fewer crowds, the weather is typically nice, and the sea is usually still ok for a dip! In November, however, the temperatures usually start to rapidly decrease, so this is really the transition to winter.

The highest sea temperature measured in the Adriatic Sea in Croatia

Measured by Croatian Meteorological and Hydrological Service, the highest sea temperature in Croatia was recorded on island Rab in 2015 and it was 29.5° C. At that time, we were on Dugi Otok and I was pregnant with our first child - I remember I couldn’t even refresh myself because the water was so warm

Location and size of the Adriatic Sea

Here’s a little background about the location and size of the Adriatic Sea (which is responsible for its mild temperatures).
The Adriatic is a relatively small sea, but borders six countries: Croatia, Italy, Slovenia, Bosnia, Montenegro and Albania and was a very important passage throughout history to get to Western Europe.
It sits between the Dinarides and the Apennine mountain ranges and connects with the Ionian Sea, which then connects with the Mediterranean (so it’s included as a part of the Mediterranean Sea). Most of the major port cities that run along the Adriatic actually started out as ancient Greek or Roman settlements. 

Size of the Adriatic Sea

ts length is just under 800km long, its average width is about 250km, and its average depth is about 175m. Because of its relatively small size (and it’s temperate climate), the sea stays pretty mild throughout the year - almost never freezing. It gets pretty warm through the summer months, and it stays relatively warm in the fall, from being heated all summer.  

We hope you’ve found this blog helpful in deciding the best month to visit Croatia and swim in the sea! We personally love the summer when it’s at its warmest because we have 3 small kids, but we also very much enjoy June and September. The Adriatic is such a clean, beautiful sea, we think you’ll love it (no matter the month you come).