Water temperature in Slovenia

Slovenia's rivers, lakes and short coast

Slovenia is above all a river country. The emerald Soča in the west, fed from the Julian Alps, stays cold even in high summer, while the Krka in Lower Carniola flows more gently and warms considerably. The Sava, Savinja, Drava and Vipava shape other parts of the country, alongside Alpine lakes and a short stretch of Adriatic coast that warms in step with the rest of the northern Adriatic. Rivers and lakes usually peak in July and August and cool quickly in autumn.

All 174 sites come from the Slovenian Environment Agency, ARSO, which records water temperature continuously at its hydrological stations. Almost all of them are on rivers, with lakes and sea represented by just a few points. The values are measured rather than modelled. They reflect conditions at each station, so swimming spots further downstream or in sheltered coves may differ slightly. For a trip to the Krka or the Soča, they still offer reliable guidance.

The National Institute of Public Health tests bathing waters during the season, with ratings from excellent to poor under the EU Bathing Water Directive. In mountain rivers like the Soča, cold water and strong current are the main hazards, even where the surface looks calm. Thunderstorms in the mountains can raise water levels quickly. On the coast, the bora brings cooler water and waves, and sea urchins on rocky ground make water shoes a good idea.