Emily Post explains that a wide variety of styles might be appropriate for a mid-afternoon wedding, and suggests that the invitation should offer some guidance as to whether the affair is formal, semiformal or informal. If the invitation is not clear, the location of the reception can also offer some guidance.
For men, tuxedos should not be worn for a daytime wedding, unless the invitation specifically states black or white tie, or in cases where the reception is held in a ballroom, according to GQ Magazine. GQ further suggests that navy or gray suits are good choices for nearly all weddings, that ties are strongly advised for all but the most casual weddings and that it's acceptable to wear slacks with a shirt and jacket for informal weddings only.
For women, Weddings.com states that a daytime wedding might suggest everything from a long ball gown in the most formal situations to an elegant cocktail dress or a simple cocktail dress and heels for semiformal occasions. For casual weddings, the same source presents the options of simple dresses with heels or flats, or a dressy skirt and top combination. Some women may prefer to wear a pantsuit instead of a skirt, dress or gown.