Surf Life Saving New Zealand club support officer Otago-Southland Maddy Crawford said lifeguards would be on duty between noon and 5pm over the weekend.
Recently, she had noticed an increase in the number of people, including out-of-town visitors, swimming at Dunedin beaches, including Smaills Beach, which were not covered by holiday surf patrols, Miss Crawford said.
There were rips at both Smaills and Tomahawk Beaches.
The growing use of Tomahawk Beach by swimmers was a key factor in extending holiday surf patrols to that beach, she said.
Weather conditions were rapidly changeable, and swimmers at patrolled beaches were urged to swim between the flags, she said.