Eastern upper New Zealand is under serious threat from beach erosion as a big offshore low, large waves and king tides combine to swamp the coastline.
WeatherWatch warns waves of 4 to 6 metres are pushing in across eastern beaches from Northland to Hawke's Bay with dangerous currents and messy surf due to the strong and even gale-force winds.
And with king tides increasing over the next few days, there are fears of not only coastal erosion but even possibly coastal inundation in some very low lying areas.
"The king tide is coming up - so I think Tuesday and Wednesday - those are the days where I think we'll find this co-occurrence of the highest waves and the highest tides," NIWA principal scientist Chris Brandolino told The AM Show on Monday.
WeatherWatch says the beaches at highest risk are those facing east in the upper half of the North Island, in particular beaches like Waihi Beach which suffer from coastal erosion anyway.
Beaches in the Coromandel have already taken a beating, with high tide and large waves on Sunday combining to flood roads.
The wild weather sucked away over a metre-and-a-half of sand dunes from Mercury Bay, with local Civil Defence Controller Garry Towler warning the hammering will continue over the next few days.
"We have had reports from around the eastern seaboard of huge tides, waves across roads and entire beaches wiped out," Towler said on Sunday.
"Huge seas, strong winds, high and king tides over the next few days will likely cause inundation, storm surge, erosion of beaches and damage to the foreshore."
Council contractors have been frantically working on Monday to protect what's left of their beaches, using heavy machinery to move sand and rocks into temporary fortifications.
But they're in a race against time before the next high tide tonight and king tides forecast later this week.
