The Slovenian Riviera packs Piran's Venetian-tiled old town on a peninsula, the Sečovlje salt pans still worked traditionally, and a 47km coastline that's mostly accessible by promenade walk between Koper and Portorož.
Sea warming for swimming, Piran cafés along the Tartini Square full, and the Sečovlje salt pans at peak salt production with spa baths in the mineral mud.
Coast at peak with Slovenian, Italian, and Austrian beach crowds, Piran Saltworks Day in late August, and the Tartini Festival of classical music.
Sea at warmest, Piran Salt Festival, and the coastal walking pleasant in autumn light without summer parking pressure.
Mild Adriatic winter around 11°C, Piran's old town walkable in cool air, and the Sečovlje saltworks museum atmospheric in winter mist.