Some vulnerable residents have been evacuated, while there is widespread flooding on Auckland's motorways and roads.
The new Minister for Auckland Michael Wood says volunteers have been out in his Mt Roskill electorate helping to evacuate vulnerable residents.
There are also reports of flooding and landslips in Devonport, Auckland Emergency Management says.
Aucklanders have endured heavy and persistent rain since after midnight. It intensified after 5am.
As dawn broke, surface flooding and water pooling eres evident in some places.
There are deep pools in dips in roads around Sandringham, St Lukes and near Eden Park and flooding in Onehunga and Devonport and around Glenfield /Wairau where there was extensive flooding on Friday. Dominion Road at the intersection with Peary Road has surface flooding.
Waka Kotahi says numerous sections of Auckland's motorways are flooded due to significant rainfall, with some sections unpassable.
It asks people to delay travel if a motorway on their route is affected, and check the agency's online traffic map for details.
Auckland emergency management says the worst of the weather is moving south, but the region isn't out of the woods yet.
Duty controller Rachel Kelleher told Morning Report there has been some localised flooding but the scale is far less than Friday's deluge.
The red heavy rain warning, severe thunderstorm watch, and the strong wind watch all ended for Northland at 4am.
-RNZ