Costa Smeralda in January

May through September offers the warmest weather, but each month brings trade-offs. May sees comfortable 22°C temperatures and empty beaches, but some restaurants and beach clubs remain closed. June hits the sweet spot — warm enough for swimming, fewer crowds, and everything open. July and August bring 30°C heat, packed beaches, and prices that double overnight. The sea reaches its warmest in September, around 24°C, while crowds thin and hotel rates drop 30%. October extends the season with mild 20°C days, though afternoon thunderstorms become common and many seasonal businesses close by month's end.