If the wires or contacts are exposed, I'd be concerned about splashing more then anything. If you have some sort of acrylic shield for the light to protect it from splashing, that would help significantly. I DIY'ed my lights and put an acrylic shield because I have fish that jump, and that small bit of water from the fish mixing with electric could short out some LED's or worse.
If the canopy was completely enclosed, I might get concerned about humidity condensing, but you said it has an open back, so unless your whole house was condensing in the summer, I wouldn't worry about it.