Had a quick stop at chiemsee was nearly 40 degrees. We all had a little paddle in the lake to cool down. We looked across the water and could see a storm coming in so quickly got back in the van and on the autobahn. Unfortunately everyone else thought the same and fortunately as it was station Stu saw a little farm track that we nipped onto. As we came off a bit of rain started so we stopped so I could pop into the back to shut the roof vent. As I was just about to step out to get back in the front Stu shout and literally golf ball size hale came crashing down. The noise was unbelievable. Stu had to hold the windscreen so it wouldn't crack. We were parallel with the autobahn just 100 m away but could hardly see them. No one could move anywhere. All in all lasted about 20 minutes. But was so loud I thought the sky was falling down. We carried on the farm track for a while the briefly back on and then off again to avoid bank holiday traffic. We headed back into Austria to Mayrhofen.