Waves could reach 6 metres high in Wellington tonight

Wellington's south coast is forecast to experience waves as high as 5m. Photo / Mark Mitchell

Authorities are warning those living in the Wellington region's coastal areas to be prepared for waves of up to 6m-high tonight.

MetService has issued a heavy swell warning for Wellington and the Wairarapa, which is expected to affect coastlines from 6pm until 11pm.

Wellington Region Emergency Management Office (WREMO) has reported Wairarapa is likely to experience a combined wave height of 5.5m to 6m overnight.

Wellington's south coast is forecast to experience waves as high as 5m.

WREMO acting regional manager Dan Neely said people living in exposed coastal areas should be prepared for surface flooding, debris, and waves washing up driftwood, seaweed, sand, and gravel.

"For people whose properties have previously been affected by swells, in the Wairarapa or south coast of Wellington, we recommend they start thinking about ways to reduce impacts of swells on their property, such as using sandbags or barriers and moving things off their front lawn and driveway."

People should be careful when driving along roads directly exposed to the sea such as Cape Palliser Rd, Tora Farm Settlement Rd, Mataikona Rd, and the Wellington south coast including Owhiro Bay Pde, The Esplanade, Moa Point Rd, Breaker Bay Rd, Marine Pde, Seatoun, Lyall Bay Pde and Karaka Bay Rd.

Wellington City Council has advised roads along the south coast will be temporarily closed if big waves start to cause damage.

Debris was washed on to the road on Wellington's south coast earlier this week. Photo / Supplied

Council contractors have a truckload of sandbags for distribution to residents in low-lying houses on Owhiro Bay Pde. The sandbags will be distributed this afternoon.

Meanwhile, occupants of campervans in the Red Rocks carpark at the western end of Owhiro Bay Pde have been advised to move to less exposed parts of the city.

It's the second heavy swell warning issued in these areas in the past week.

Neely said warnings like this would likely become more common in the future due to climate change.

"We urge people in these areas to be aware of coastal hazards and take steps towards getting prepared for events like this.

"This could include creating a household plan, getting to know who in their street may need extra assistance and having a grab bag ready, in case they need to leave quickly in future."