Is it possible to source a C-Bus switch which is weatherproof?
There are no C-Bus switches made as weatherproof. There are 2 options for solutions.
1 - Install a product such as a cover, flap or shroud that protects a C-Bus switch better. E.g. 255, 223H, WS226.
2 - Any general electrical switch can be 'coupled' to C-Bus so it can act as a C-Bus switch on the network.
The C-Bus Bus Coupler part name is as follows 5102BCLEDL or 5104BCL.