UPDATED 9.14pm: Firefighters are scrambling to deal with flooding in homes in West and South Auckland, after heavy downpours in the city.

The Fire Service says it has been to 50 flooded houses since 6pm.

There are reports of downpours so intense cars are floating in an Auckland street.

The Fire Service says the calls have come from residents of Chichester Drive in the suburb of Rosehill.

It's been called to the suburbs of Titirangi, New Lynn, Ranui, Kelston, Glen Eden, Green Bay, Te Atatu, Henderson and Blockhouse Bay.

A Countdown supermarket in Te Atatu South is reported to have issues too.

In southern parts of the city, properties in Papatoetoe, Weymouth, Clendon Park and Totara Heights have been impacted.

Some residents say their backyards look like swimming pools.

Many parts of New Zealand face a night of heavy rain, rising river levels and possible surface flooding.

A severe weather warning in place for heavy rain in Westland, the northwest Nelson Ranges, and western Bay of Plenty.

MetService has recorded more than 40 thunderstorms over the past few hours, mostly offshore from Northland.

Heavy rain is also expected for Buller, Canterbury and the Coromandel Peninsula.

Meanwhile passengers at Auckland Airport are having to dodge water leaking at the terminal.

The wild weather has caused leaks at several places including the Koru lounge.

Auckland airport says they are dealing with it.

A spokesman says the control tower is not affected.

Power is out to more than 1600 properties in East Auckland.

Vector says it's been caused by a feeder fault.

It's impacting suburbs including Kohimarama, Mission Bay, St Heliers, Orakei, Glenn Innes and northern parts of Panmure.

Vector hopes to have it back on by 8.30pm.

Civil Defence says anyone with flooding inside their property should call 111.

For blocked stormwater drains, people should call the Council.