May through September is by all means the best time to visit Austria. The weather remains dry, warm and sunny which makes it a perfect season for fun-filled activities from mountain biking to hiking. The only drawback is a surge of tourists and higher room rates, so if you prefer to avoid crowds, choose late spring or early autumn.
Winter is appreciated for thermal baths and events like Snowbombing Festival. It is a fantastic period for skiers and snowboarders as well as for those looking for a true Christmas spirit.