Summer in Austria is great. The picture above is from Wolfgangsee. It is in these surroundings the film "Sound of Music" was recorded. It is located in a region called Salzkammergut. Here you will find many beautiful lakes and are a summer gem. These lakes often hold 20°C or more in summer and are popular as bathing spots. The nearest major city is Salzburg.
There are also many fine lakes in the bundeslandet (county) Carinthia. Mes known is probably Wörthersee. We can also recommend Faaker see, Ossiacher see and Millstättersee.
Many of Austria's gondola lanes and chairlifts run in the summer. It provides a great starting point for hiking in the mountains.
If you are interested in wine and wine cultivation, there are opportunities to visit vineyards and learn more about wine. These farms are mostly located in Vienna, Lower Austria and Burgenland. You can read more about this here.