18 Septemba bu ubochi nke 18th (nke iri na asatọ) na onwa ana kpo Septemba. Na Gregorian calender, 18 Septemba bu ubochi nke 261st (262nd na afo nke ana-kpo leap year) na afo. Anyi nwere agugu ubochi 104 du mgbe afo na agwu.