UPDATED 10.00am: Auckland's Tamaki Drive has now reopened after heavy rain and a big sea have combined tom make driving treacherous.

Peak tide is at 9am.

There's also flooding around the motorway off-ramp at Fanshawe St.

Kay Gregory said traffic is backed up for five kilometres along Tamaki Drive.

"The sea is really rough, there's been torrential rain in this part of Auckland. Lots of drains have overflowed, there's quite a bit of surface flooding. Making a trip into the city will be from this part of Auckland will be really difficult."

New Zealand Transport Agency Auckland and Northland spokeswoman Sarah Azam said the agency was monitoring the situation closely.

"Obviously the weather is marginal and where possible we've got signs up for motorists to take extra care," she said.

"We're closely monitoring the situation, we're working with contractors to resolve issues as soon as we can."

Flooding in the north near Brynderwyn and Otaika meant drivers should take extra care, she said.

It is taking about 40 minutes to drive into the city from Greville Rd, 45 minutes from Hobsonville and more than 90 minutes from Papakura, NZTA tweeted.

WAIKATO

Waikato motorists are being urged to use extreme care on the roads and avoid unnecessary travel.

Several Coromandel roads and schools are closed, and most Coromandel school buses aren't operating.

Hikuai Settlement Road into Hikuai, Tairua Road into Tairua are closed, and State Highway 25 between Tairua and Whangamata are closed.

State Highway 2 between Paeroa and Waihi could be closed due to rising river levels in the Karangahape Gorge.

There is flooding on East Coast Road to Kaiaua, Thames Coast Road and Kopu-Hikuai Road.