Swells hitting Hawke's Bay from the remnants of Cyclone Cody are expected to begin to ease tomorrow.
This afternoon the swell was slowly building, with damage to exposed areas at high tide after 6pm still possible.
But for the most part, the region and New Zealand had been "spared the full brunt of this storm", with the storm moving even further east today .
MetService meteorologist Luis Fernandes said strong winds around the cyclone had generated large swells.
Easterly swells were at a height of 2.3 metres at a sheltered area near Napier Port at about noon, and were expected to rise 3.5 metres around the Hawke's Bay coastline by evening.
The worst of the swells should have rolled through by Tuesday morning and they would slowly die down from that point, he said.
"Big swells have been affecting the northern coastline of the North Island since the start of the weekend."
Maximum wave heights measuring close to seven metres had been recorded in the Bay of Islands, "really significant" for the usually sheltered area, MetService said.
Fernandes said while the tsunami from the Tongan eruption was measured in Aotearoa, the consistent big swells were directly attributed to Cyclone Cody.
Hawke's Bay Civil Defence Emergency Management Group (HBCDEM) is advising boaties and beachgoers to stay out of the water until Wednesday.
HBCDEM group controller Ian Macdonald said it was likely that the region's coastline will experience significant waves and hazardous sea conditions through Tuesday.
Fernandes agreed, saying: "The large swells were spreading down the east coast on Monday and could still produce dangerous rips for the inshore areas of Gisborne and Hawke's Bay on Tuesday."
A ship was today anchoring off the coast of Napier rather than in port, as a precaution.
Napier Port's docks were this morning all but empty and a Napier Port spokeswoman said the effects of Cyclone Cody the eruption of volcano Hunga-Tonga-Hunga-Ha'pai were partially to blame.
"Based on forecasts and potential strong swells, we have one ship out at anchor, as a precaution.
"We'll be watching this carefully," the spokeswomen said.
Hawke's Bay residents have been on high alert after a tsunami surge struck the east coast on Saturday night, causing widespread damage in a Northland marina and "unusual currents" and "unpredictable surges" in Hawke's Bay.
That surge included one videoed in the Ahuriri Estuary on Sunday afternoon.