Swells forcing evacuations of beachfront properties on the Hawke's Bay coast are up to 5.5 metres high.

Locals say one wave was higher than a house.

Police have told 21 residents at Haumoana and Ocean Beach to leave their homes. Senior Sergeant Ross Smith is also advising people to stay off beaches right along the Hawke's Bay coastline. He says the swells are the worst in 12 years.

A road block has been set up at Ocean Beach to keep sightseers away.

MetService says the swells should recede over the next few days.

Meanwhile heavy swells on the Wairarapa's east coast have forced the cancellation of the annual horse racing on Castlepoint Beach. They were due to be held in a fortnight, but pounding waves have stripped the entire beach bare of sand.

The Castlepoint Racing Club says it is left with no choice but to cancel.