The previous blog listed seven planning strategies. There are good reasons to implement them in your plans so you can hear all the music you contracted.
Protecting the musicians from the elements insures that they can actually perform for you. They need to do their job what you need to do yours: dry level ground, lighting, electricity, and comfortable temperatures. Direct sun ruins instruments and creates an unreadable glare on the sheet music. Music stands fall down in the wind, and rain ruins both instruments and sheet music, and creates an electrical arc on cords. Musicians will stop playing at the first raindrop. Cold weather, under 65 degrees, prevents instruments and fingers from playing and causes guests in their formal attire to seek out quilts for warmth.
Please keep in the mind the best outdoor wedding months and times. My best story is the bride who told me that her 8 pm December 17 outdoor garden wedding would be fine because we had global warming!!!