Piran in October

May through September gives you the best weather and everything open. July and August bring crowds and €200+ hotel rates, but the sea is warmest then. June and September hit the sweet spot — warm enough for swimming, fewer tourists, and restaurants still operating full menus. The Tartini Festival in late August fills the square with classical music concerts. Winter is quiet but charming in its own way — many restaurants close, but you'll have the medieval streets mostly to yourself. Just bring a jacket; the Bora wind off the Adriatic can be fierce. Spring arrives early here, with pleasant weather starting in April, though some seasonal businesses might still be closed.