From a weather point of view the best time to visit Salzburg is between June and early September. The average daily high temperature during this period is 24⁰ C but can reach 35⁰C in a good summer. But beware this is the peak time for rain! This paradox is because Salzburg is situated on the edge of the Alps and moist air in the summer gets trapped in the mountains. This results in rain in the Salzburg area. The rain can be so bad the locals have a name for it “Schnürlregen” which means rain in strings. This is not necessarily a bad thing as a downpour in the late afternoon on a hot humid day can be refreshing, just be prepared. The thunderstorms themselves can be very dramatic, lighting up the mountains and thunder rolling around the valleys.
For winter activities the cold season is from late November to early March. Daily average temperature during this time is 7⁰C but can drop to -4⁰C during the day and considerably colder at night. During this time you can expect snow on the mountains and in the higher valleys. Snow in Salzburg is likely during January and February.
The main message for the visitor is be prepared and have a plan B for your activities. If its really raining, the Haus de Natur Museum can be crowded so best choose another rainy day activity. The Norwegians have a saying that there is no such thing as bad weather – just the wrong clothing.
For a month by month guide see below. Remember that weather anywhere can be fickle and hard to predict so this is just a guide.