Motorists are being warned to take care on Auckland Harbour Bridge tonight as the city is buffeted by strong winds gusting to gale force.
There are also warnings of power cuts as winds peak and bands of heavy rain cross the city.
The rain and wind drenching parts of the country today will continue through the evening, with heavy rain watches in force for Northland and Auckland.
WeatherWatch says winds are peaking across Auckland now with northeast gales in exposed places.
"Take care driving on the Harbour Bridge next 60 minutes in particular, with heavy rain and gusts to gale force.
"Isolated power cuts are possible between 6pm and 7pm as winds peak and heavy rain moves through."
MetService meteorologist Tahlia Crabtree said the wet weather and strong winds in Auckland would continue into the evening.
"It's not going anywhere. It's just going to get worse."
The forecaster has issued heavy rain watches for Auckland and Northland, warning residents that thunderstorms are possible.
The downpours are expected to begin easing in Northland from 1am and to ease a few hours later in Auckland from 3am.
Areas MetService has heavy rain warnings for could see rainfall amounts increase by another 30mm over the next 12 hours, Crabtree said.
Stations across Northland, Auckland and the Coromandel had recorded gusts over 65km/h.
"I imagine Bay of Plenty will get pretty windy over the next few hours and the brunt of that wind will be picking up around Auckland as well in the next couple of hours," she said.
A heavy rain warning for Bay of Plenty, including Rotorua, will come into force this evening, with up to 120mm expected to fall along the eastern coast from about 9pm tonight.
Peak intensities of rainfall could reach 20mm to 30mm per hour or more during Wednesday morning.
MetService duty meteorologist Andrew James said the rain is the result of a low-pressure system swinging down from the north, which will bring warm temperatures but copious amounts of rain.
While the whole North Island will see some level of rain, just the tip of the South Island to Blenheim and Nelson would be affected by heavy rain, James said.
"This warm air from the north does tend to bring what we call unstable conditions, which lead to the possibility of thunderstorms, so all through that upper North Island is the area where we would expect those."
There was also an "outside possibility" of mini tornadoes but where and when was anybody's guess, James said.
"Where and when they pop up is not really something that's able to be forecast."
By tomorrow morning it will likely be all over for Auckland and Northland, but Bay of Plenty will feel the effects a bit longer.