The National Institute of Water & Atmospheric Research is warning that coastal erosion could claim some beachside properties if they are not moved.
In the last year, Punakaiki Beach on the West Coast has dropped by 2.5 metres and recent king tides have damaged a sea wall protecting 10 baches.
And just south of Oamaru, the Waitaki Council moved Beach Road inland three times before closing parts of it that have eroded into the sea.
NIWA says mother nature will eventually win the battle against some communities.
The organisation's coastal process engineer Doug Ramsay says some tough decisions will eventually have to be made about what to do with properties in danger of being swept away.
He says building sea walls to protect the coastline is often futile, and over the next 50 to 100 years some properties may have to be moved back from the coastline.