Traffic in Wrexham will be affected later as about 20,000 Stereophonics fans attend a sell-out concert.
North Wales Police warned motorists to expect delays ahead of the gig at Glyndwr University Racecourse Stadium.
Mold Road will be one-way out of town from 13:00-22:15 BST and will be closed temporarily after that to allow crowds to disperse.
The band performed at the stadium in 2016, the first since 1982 when Motorhead entertained the crowds.
Chief Insp Mark Williams said: "With such large numbers converging on the town it is important that people, especially those who are not going to the concert, are aware that it will be an extremely busy day and to bear this in mind when out and about."
Wrexham council said Mold Road should reopen before midnight.