An Auckland motorway has flooded as a band of torrential rain batters the top half of the North Island.

It's been a wet, blustery morning for Auckland, with motorists warned to watch out for hazardous driving conditions as strong winds, heavy rain and thunderstorms are forecast for the city.

By mid-morning flooding on State Highway 1 near the East Tamaki off-ramp had forced the closure of the northbound lane, and motorists were being urged to expect delays and drive carefully.

The wild weather has caused a Waiheke ferry cancellation, leaving 10am commuters stranded.

MetService meteorologist Luis Fernandes told the Herald the Harbour Bridge saw gusts of up to 80km/h in the early hours of the morning, and the rest of Auckland should batten down the hatches as the wild weather continues.

"For the rest of the morning, the next few hours at least Auckland is going to stay very wet with persistent, continuous rain - there's going to be no point today when we can say 'oh it's clearing up'."

Fernandes says overnight some exposed areas in Northland had wind gusts over 100km/h, and just under 60mm of rain fell in Kerikeri in the hours from midday yesterday.

MetService says a severe weather warning is in place from 6pm last night through to 9am today.

A heavy burst of rain hit Auckland soon after 5.30am today, causing surface flooding in some CBD streets.

"We are expecting heavy rain from [Monday] morning to around 3pm tomorrow afternoon, with that there could be some thunderstorms and localised downpours also," MetService said.

"Behind that front, the rain turns to showers but they could still be pretty sharp. There is a watch for strong wind from tonight until tomorrow morning."

Waka Kotahi transport agency said that winds of up to 85km/h could see lanes on the Auckland Harbour Bridge required to closed.

Maintenance crews are ready to close lanes if wind gusts exceed the safe use thresholds.

Motorcyclists and drivers in high-sided vehicle should avoid the Harbour Bridge and use the Western Ring on State Highways 16 and 18.

Earlier, heavy rain warnings were issued for other parts of the country including the Far North and Gisborne.

- Additional reporting: RNZ