Better to have a tie and not need it than to need a tie and not have it.

Ask the client how they want the photographer to dress and, in the absence of information to the contrary, wear a coat and tie. You could always take off what you don't need. Leave the coat or tie in the car if you decide they aren't needed.

My stepsister recently got married on the beach. All the men wore dress pants and shirts with ties loose at the collar. Most of the women wore dresses but ended up going barefoot in the sand.

Made for some interesting photos! (Click.)

Bottom line: Blend in.