Originally posted by mattb123 Just don't change lenses outside if the snow is flying!
IN all seriousness, as long as you don't go out in a driving rain and stand out there getting soaked, and as long as you brush off any snow from the connection of body and lens before the snow melts, you will do OK. I go out in bad weather fairly often with whatever lens is at hand. I Keep the camera covered in its bag until I am ready to shoot, shield the camera with my body or tuck it inside my coat. etc,, or standing in a doorway, and avoid facing into the wind, and wipe down the camera afterwards. Also, if it is very cold/freezing, and you enter a warm room from an extended period outside, do not open the camera to change lenses, wait at least 30 minutes until it has warmed to room temperature. This prevents condensation from forming inside the cold camera.
I don't have a 15mm, I use a takumar 17mm quite a bit. I do own the 40mm XS, it is a great walk-around lens in a city.
Have fun, Muenchen offers so much to see both indoors and out. I like to sit on the second floor of the train station and watch the crowds while taking long exposure pictures. The Englsih garden is always fantastic, and the old town as well.