Weather: ~24 °C, dry
Timing: last day of May
Half of the day as a quick stop
Small city, that is just on the way to Italian Dolomites, worth to quick stop, though.
As in pretty much entire Italy, Bolzano offers wide selection of great local food, also nice sights in the city itself and lots of shops to get alpine gear, some souvenirs. City is compact enough to make quick look around and big enough to host you for bit longer visit before going further to the Alps.
Our choice was to plan for half of the day there, to just come by car and walk around in between our visits of the Dolomites. It was enough time to grasp Bolzano.
Bolzano is also home to Ötzi the Iceman, a well-preserved natural mummy of a man that you can see in the South Tyrol Archeological Museum.
Another interesting idea is to visit Messner Mountain Museum Firmian, just an important note, that not all parts of the museum are open year-round!