Rips and conditions off Hawke's Bay beaches have changed significantly since the November storm that dropped more than 200mm of rain in 12 hours.
The region's lifeguards have warned that rips may have moved since the storm and flooding, creating more hazardous conditions.
Ocean Beach director of lifeguarding Matt Mannington said beach goers must be cautious ahead of the first weekend of summer.
"One of the main things for this season is the storm we had a few weeks ago that flooded everything.
"It carved up the beaches and quite a lot the rivers have opened up again, especially at Ocean Beach," he said.
Mannington said a change in where rips were forming was noticed on their first few patrols.
Although there have been no rip related issues so far at the beach this season, Mannington said lifeguards have had to change their usual routines.
"We've had to set up the beach completely differently to the way we usually do," he said.
He said there are more rips closer to the car park at Ocean Beach.
"That's the easiest place to walk down to, so we are concentrating on those areas a bit more," he added.
Rip currents are one of the most dangerous elements on New Zealand beaches.
Surf Life Saving New Zealand (SLSNZ) chief executive Paul Dalton said it's vital for every kiwi to memorise the 'three Rs' – relax, raise and ride.
Anyone caught in a rip is encouraged to relax and float to conserve energy, raise their hand to signal for help and ride the rip until it stops and they can swim back to shore or when help arrives.
Dalton said new data shows rips are one of the main causes of incidents and drownings on New Zealand beaches.
"Over the last 10 years, 39 per cent of fatal drownings in the coastal environment – up to 1km offshore - occurred on surf beaches, which are notorious for rips," he said.
Popular Hawke's Bay swimming beaches including Westshore, Waimarama, Waipatiki and Ocean Beach are also all surf beaches.
A rip is a narrow body of water moving out to sea like a river.
These currents are caused by complex interactions between the ocean – such as tides and swell – and the shape of the sea bed.
SLSNZ national coastal safety manager and seasoned surf lifeguard Mick Kearney said people need to choose a beach with lifeguards on duty.
"The surest way to avoid getting caught in a rip is to stay out of the water if you're unsure of the conditions or your own physical limits," he said.
"Choose a lifeguarded beach where possible and always swim between the red and yellow flags."