Dangerous swells are set to arrive along the country's western coasts on New Year's Day and beachgoers need to be on the lookout, MetService says.
The weather forecaster is warning of waves that will begin building up from Monday morning.
"[The] swell is expected to rise on west coast beaches during New Year's Day, which could take beach users by surprise," it said.
"Waves may not appear large at first but will rise through tomorrow."
The swell is being produced by persistent gales south of Australia.
New Year celebrations are expected to be generally met with fine weather in northern and eastern parts of the country, with some rain towards the west.