Dubrovnik’s big sea temperature drop mystifies experts

Dubrovnik

In the midst of summer, during a period when high temperatures are expected both in the air and in the sea, residents and tourists in Dubrovnik and the surrounding areas got caught by surprise by a sudden drop in sea temperature.

Yesterday, the sea was pleasantly warm for swimming, but today many report it being unusually cold.

According to the Croatian Meteorological and Hydrological Service (DHMZ), the sea temperature this morning at 7 AM was just 19.1°C, and by 11 AM it had only risen to 19.6°C.

This represents a dramatic drop from the record temperatures recorded a few days ago, when the sea reached around 30°C, as previously reported.

To understand the causes of this phenomenon, Večernji list consulted experts for an explanation.

Ivica Vilibić from the Ruđer Bošković Institute commented on the situation, emphasising that the current drop in sea temperature is influenced by atmospheric temperature changes.

“The sea temperature is affected by several factors. Primarily, heat transfer from the atmosphere to the sea causes the sea to warm from spring to the end of summer, when solar radiation is at its peak.

The warmer the air, the warmer the sea surface, hence the record temperatures during the recent heatwave. In autumn and winter, the sea cools as it loses heat to the atmosphere, giving coastal areas a warmer climate.”

Vilibić also explained how the bura wind can dramatically affect sea surface temperatures:

“When a stronger bura blows in the summer, it triggers upwelling, pushing surface water towards the open sea and causing colder, deeper water to rise along the coast. This phenomenon can significantly lower the sea surface temperature.

In the Dubrovnik area, a relatively strong bora has been blowing, pushing the warmer surface water towards the Italian coast and bringing colder water up to the shore. This is a regular occurrence in the summer, following a heatwave or normal summer period. Once the bura subsides, it will take a few days for the sea to return to its usual temperatures,” Vilibić said.

On the other hand, Natalija Dumić from the Institute of Oceanography and Fisheries in Split expressed her surprise at the temperature drop, but disagreed that it was solely due to the bura, noting that the current air isn’t that cold.

“I find this number strange too, but I wouldn’t draw any conclusions until the temperature drop is confirmed over a couple of days. Many factors, including human error in measurements, can influence a brief temperature drop.

Such a rapid drop isn’t natural, but without consistent readings over at least two consecutive days, it’s hard to comment. The bora might play a role, but here in Split, it’s not cold enough to cause such a significant temperature drop. There could be other factors or measurement errors involved,” Dumić said.

Dubrovnik

The DHMZ confirmed that they are rechecking the data as they are also surprised by the sudden drop in temperature. Further analyses and a subsequent report on the possible causes and confirmation of this phenomenon are expected.