The swells - which may be more than 5 metres - could hang around the Wellington coast until 8pm tonight.
The mountainous seas out of Cook Strait of up to 4.5m high were projected to hit between Baring Head to Sinclair Head overnight.
The Wellington Region Emergency Management Office is urging residents on the coast to have an up-to-date household plan.
Heads up Swellington🌊
Swells along the south coast of the capital rapidly pick up tomorrow, where there's a Heavy Swell Warning from morning. With high tide around late morning, remember to take extra care as this will be the highest risk period https://t.co/qHyE5zhh6X ^MM pic.twitter.com/3rVI7bYEt2
HEAVY SWELL WARNING - Baring Head to Sinclair Head MetService has issued a SWELL WARNING for Baring Head to Sinclair Head for this SUNDAY 22 November. This is a good reminder to check you have an up to date household plan. The WREMO Duty Team
— Wellington Region Emergency Management Office (@WREMOinfo) November 20, 2020