Jun 4, 2011 - 12:29 PM
I agree with SwissMountainLeader that drizzles/light showers won't keep you from hiking and biking assuming you have the proper clothing (light, breathable waterproof shell with hood). The mountains are actually very beautiful to see when weather is moving through.
That said, there are lots of things to do in the area if the weather is really bad. I have a 30+ page write up on Wengen area that includes stuff to do when it's really raining (such as Lake Brienz cruise, Ballenberg Museum, Lauterbrunnen valley walk/Trümmelbach Falls). Happy to send it to you. If you're interested, send me your email address in a private message.