In case those weather messages would be ever implemented (something I really doubt) then they would be implemented in both languages as everything in the game that is script driven.
*shrugs* There were German only messages broadcast in game today and a lot of confusion when I couldn't play along. Apparently the messages had something to do with the weather, but the graphics showed clear weather.
The messages today where indeed only in German but they where not automated weather messages. It was a GM giving messages about the weather for some reason.