Wellington Mayor Andrew Little declared a state of emergency on the eve of the swells for seaside residents in Owhiro Bay, Island Bay, Houghton Bay and Breaker Bay.

"You must stay away from the southern coastline," Little said in a statement, warning that emergency workers would not be coming to help anyone who stayed behind.

The evacuation order took effect on Tuesday morning, with police brought in to ensure people moved to higher ground.

Officers set up cordons on surrounding roads to prevent people from heading to the coast.

The council said a similar event in 2021 affected many homes in Breaker Bay, and waves during that storm were about 6.5 metres.

Waves entering Wellington Harbour on Tuesday were measured at 11 metres, New Zealand's MetService said.

Wind gusts were so strong at Island Bay that two women were knocked off their feet as waves washed up over the road, an AFP journalist saw.

Some flights were cancelled at Wellington Airport where wind gusts were recorded of up to 128 kilometres per hour (80 miles per hour).

A small plane from local carrier Golden Bay Air tipped onto its side in the wind while parked at the airport with no-one aboard.

Airline boss Richard Molloy told national broadcaster RNZ that fire fighters had secured the plane to the ground.