The mercury begins to drop come September and the rains start to increase welcoming in the change of season, though the Adriatic is still an inviting 73 degrees Fahrenheit. In and around Portorož on the coast of the northern Adriatic temperatures average 67 degrees, while in the interior of the country around Ljubljana the weather is a little cooler and wetter with an average of 62. The mountains are coolest of all with lows of 43 degrees and highs of 64.
Crowds & Costs
September is one of the best months to travel to Slovenia. The crowds start to thin out as locals return to the office, children go back to school, and foreign tourists head home. The weather is still warm enough to encourage plenty of outdoor activities, including swimming, and flights and tourist attractions are less costly than in peak season. Hotel prices, too, begin their six-month decline.
Where to Go
The weather is more comfortable and the crowds have started to dissipate, making September a smart time to visit popular attractions that would otherwise be cumbersome to explore.
A popular route option would be to begin or end in Ljubljana, and work your way south to Predjama Castle and into the Slovenian Istria. From there heading up along the 30-mile coastline, stopping at the medieval seaside towns, like Portorož, Piran, and Koper to take in the sights and jump in the Gulf of Trieste if the mood strikes.
Next, venture through the Karst region, explore the number of subterranean cave systems, like Škocjan Caves, and continue north through Goriška Brda wine country and along the Italy-Slovenia border to Bovec, Triglav National Park and finally to Kranjska Gora up in the mountains.
Consider exploring the area east of Ljubljana, like Celje and the wine region in and around Ptuj and Maribor or head north of the city to Velika Planina.
Check out the Top Highlights of Slovenia for more ideas on where to go.
What to Do
There are endless options to consider in September, from outdoor activities to cultural events and interesting festivals. Explore cities like Ljubljana, Celje, Ptuj, and Piran, for Slovenia’s best museums, restaurants, and cultural attractions.
Photographers will appreciate heading to Triglav National Park and up into the Julian or Kamnik Alps to snap pics of the larch trees readying themselves for winter, the already stunning mountain scenery turns into an explosion of reds, yellows, and oranges. Hike or ride the ski lift up to Mt. Vogel for stunning views over Lake Bohinj or follow the walking path to Savica Waterfall.
Mix things up and strip down to your swimsuit and swim in Lake Bled—though warm enough to swim in at this time, keep in mind the waters are cool year-round. A warmer option is to paddleboard, kayak, or rent a pletna to row across the lake to the iconic Bled Island.
Alternatively, head to the Soča Valley, a haven for adrenaline junkies and nature lovers, and to Bovec, the main hub for adventure sports like canyoning, kayaking, and zip-lining. Fans of history will appreciate a visit to nearby Kobarid for a museum dedicated to the largest mountain battle in World War I. Then, choose from one of the country’s best restaurants in Kobarid and enjoy a fabulous meal.
Events in September
Slovenian Film Festival. Three-days of screenings in Portorož takes place at the end of the month.
Kraviji Bal (Cow Ball). Bohinj hosts a lively weekend of folk music, dance, eating and drinking to celebrate the return of the cows from their pastures in the highlands.
Odprta Kuhna (Open Kitchen). An outdoor food festival that takes place every Friday through to October.
Traveling to Slovenia in September? Check out these great itineraries.
Istria & Adriatic Cycling Tour - 7 Days. Discover the Istrian Coast in this relaxed weeklong tour. Cycle easy country roads through vineyards and endless olive groves, enjoy afternoon coffee in medieval town squares and soak in the casual coastal atmosphere.
Food & Nature in Slovenia - 8 Days. Go on a gastronomic and cultural journey through Slovenia. Explore Ljubljana's old town, see Lake Bled's 11th-century castle, and explore the fairytale-like landscapes of the Soca River Valley. End your trip in Slovenia's Goriska Brda region, where world-class wines and farm-to-table cuisine await.