Heavy rain, causing flooding on Auckland roads and major highways, has left vehicles floating down roads and commuters jumping on top of cars to prevent being swept away.

Photos and video show a car has been trapped in rising floodwaters on Auckland’s northern motorway. People can be seen attempting to extract the car near the Northcote on-ramp on Auckland’s North Shore.

A witness told NZME that an ambulance was racing to an emergency on the wrong way down the motorway to get through.

A car has been trapped in flooding on Auckland's northern motorway as rising water brings traffic going in both directions to a standstill. Photo / Supplied

Waka Kotahi NZ Transport agency have told commuters to expect delays or consider an alternative route.

Commuters on a bus caught in the traffic chaos were seen exiting and running as water levels rose.

Commuters exit a bus caught in traffic chaos on Auckland's Northern motorway. Photo / Supplied

Cars have been spotted near the Onehunga Basin, nearly fully submerged, as commuters ditch their vehicles and rush for cover.

Police are urging motorists to be careful and drive to conditions as wild weather continues to pummel Auckland.

“This means being patient, delaying non-essential travel, increasing following distance and being aware of fellow drivers.

 “Those travelling out of Auckland for the long weekend may experience long traffic delays and potential diversions due to road closures. Keep level-headed, allow for extra time, and most of all, stay safe. Police thank motorists for their patience,” police said in a statement.

Police also said due to hazardous conditions, diversions have been put in place on State Highway 1, Brynderwyn.

“At this stage heavy vehicles heading south can travel over the Brynderwyns. Other vehicles travelling south are being diverted at the intersection of State Highway 1 and The Braigh, Waipu.”

Heavy vehicles and vehicles travelling north are being diverted to State Highway 12.

These diversions may change, police said.

Signs at Auckland’s Britomart train station are also advising passengers that due to severe weather, services on the Southern and Eastern Lines are delayed, and some services may be cancelled.

A witness told the Herald, “nothing has moved in or out of Britomart for the last 15 minutes.”