Guest “dress Code” for Summer Wedding

Recently I have been struggling with what the appropriate guest attire will be for our wedding. I know for the most part our guest will come dressed appropriately, but I want to be sure that Incase some question what they should wear we have it outlined and no one shows up in cutoff jorts and their favorite beer T-shirt from 1985 (yes, I’m being dramatic but we live in GA so I’m not willing to take chances! 😂)
Our Wedding is in mid July, which would indicate a sundress type attire. However our ceremony starts at 6pm, which generally indicates more formal dress. My girls are wearing long chiffon dresses and the groomsmen are wearing dress pants but no jackets (being July we’re trying not to torture them too much!) My fiancé, my son, & our officiant will however be wearing jackets.
I currently have “Semi Formal” listed on our website but I am just not feeling that is appropriate. Any suggestions for how to describe guest attire for a Summer Evening wedding?