Marlborough residents are being advised to stay put as heavy rain lashes the region.
Auckland is also experiencing wild weather and commuters are being warned to take care.
Up to 70mm of rain is forecast for the Marlborough region, which was already devastated by flooding last week.
Marlborough Emergency Management controller Dean Heiford is urging people to avoid non-essential travel.
"Hunker down, keep warm and dry and don't do any travelling that's unnecessary," he told Newshub. "Some areas are still unable to be accessed by road."
The Tasman region is already experiencing surface flooding and fallen trees as bad weather batters the area.
Early on Monday State Highway 6 was briefly closed from Kohatu to Glenhope after a fallen tree blocked the road.
At 8:30am NZTA said it had reopened but urged Kiwis to take care.
"SH6 Kohatu to Glenhope is now OPEN to a single lane with a temporary speed limit in place. Please continue to take extra care and follow directions by contractors on-site," NZTA tweeted.
Heavy rain and strong wind warnings are in place for Auckland including Great Barrier Island. MetService said the wild weather will last all day.
"Surface flooding and slips are also possible and driving conditions may be hazardous," the forecaster said in its severe weather warning.
"Strong wind gusts could damage trees, powerlines and unsecured structures."
