Downpours and strong winds are hitting parts of the North Island, causing road closures, power outages and surface flooding.

On the Coromandel Peninsula, SH25 near Ruamahunga is closed in both directions near the intersection of Otuturu Crescent due to a slip.

The highway is also closed south of Whitianga by the intersection of Wade Road, and at Manaia Bridge by flooding.

In Whitianga, a car stuck on Whitianga Road was towed out of rising floodwaters by a member of the public about 9am, says Fire and Emergency.

Fire crews were called about 4am to two people stuck in their car in floodwaters in Thames, and helped move their car out of the flooding.

A slip blocked both lanes of Victoria Road in Thames after 100mm of rain fell overnight, Thames-Coromandel District Council says. The council says river levels are high, but the morning high tide wasn't expected to cause problems.

By midday about 200 properties were still without power in the Coromandel. Powerco says crews are working to restore power but some are being hampered as rain continued to fall.

Flooding prevented pumping of fresh water into Coromandel Town's treatment plant, and residents are asked to conserve water.

Hahei residents are also asked to conserve water because of an electrical fault at the treatment plant.

Orange heavy rain warnings are in place for Coromandel Pensinsula until 8pm Friday and Tai Rāwhiti until 7am Saturday.

Power outages have also been reported south of the Bombay Hills.

Downpours had caused delays for commuters on Auckland's Southern Motorway on Friday mornng, with floodwaters blocking a lane northbound just after Te Irirangi Drive on-ramp.

Ferry services between downtown Auckland and Gulf Harbour are being replaced by taxis due to the bad weather.

Auckland Transport says Oteha Valley Road has reopened after earlier flooding.

MetService issued heavy rain and strong wind watches for Auckland and Great Barrier Island until 3pm on Friday.

There are also strong wind watches for Auckland including Great Barrier Island, Coromandel Peninsula, parts of Waikato and Bay of Plenty, Waitomo, Taranaki, Taumarunui, Taupō, Taihape, Whanganui, Manawatu, Horowhenua and Kāpiti.

In coastal Taranaki, crews responded to suspected wind-damage outages in and around Ōpunake. Powerco said crews were available to fix faults and reconnect supply where they could get safe access.

MetService forecaster John Law says there's a risk that streams and rivers would rise rapidly as more rain fell.

"It is also worth bearing in mind that with a fair bit of wet weather around and windy weather as well it may make those driving conditions a little bit more hazardous as well."

-RNZ.