It is impossible to plan a wedding without thinking about how kind the weather will be to you on your big day.
No matter how optimistic you are, remember to have a wet weather plan in place. If you have booked musicians and you have to resort unexpectedly to your indoor option, there will need to be enough space to accommodate them.
Of course on the other hand, unexpectedly good weather could well enable you to have photographs outside with your guests meandering around the grounds of your venue. It is important therefore that some thought is put into an appropriate place for your musicians to set up so that your guests can enjoy their playing and the musicians can, in turn, have appropriate protection from either possible rain or extreme heat.