Metservice meteorologist April Clark said the "biggie" today would be the effect of king tides arriving at the same tide north-easterly winds whipped up heavy north-east swells, Clark said.
"[The swell and king tides] mean we are looking at the potential for sea inundation on the eastern coast from Northland through to Bay of Plenty."
There was still some uncertainty because if winds were not as strong as expected the swell would be smaller, but she urged people living in coastal areas to be aware.