Motorists are being urged to drive to the conditions with heavy downpours and thunderstorms forecast for most of the country, with roads closed in the south.

There have been heavy local downpours in Northland, the Coromandel Peninsula, eastern Waikato and Taupō while significant rainfall is falling in southern areas of the South Island.

South Canterbury and Otago are bracing for further flooding this afternoon. Rivers and streams have been rising, there's already surface flooding on roads, and a heavy rain warning has been issued.

Flooding in Otago. PHOTO: Central Otago District Council

Waitaki district mayor Gary Kircher said constant rain had continued for longer than forecast, which was a worry.

He says council contractors are clearing drains and putting flood warning signs on roads.

Central Otago campers are being advised to relocate to higher ground, as continuing heavy rain causes river levels to rise. State Highway 6 is now closed between Frankton and Kingston.

MetService has issued a heavy rain warning for North Otago, Dunedin and Clutha from Balclutha northwards until 3am tomorrow. It said up to 100mm more rain could fall, on top of what has already fallen in the area.

It warned it could cause floods and rivers to rise rapidly, surface flooding and slips.

There have also been thunderstorms and heavy rain across the North Island this afternoon, with 37.6mm of rain reported in one hour in Whangarei.

The storms have now headed east, and are closing in on Hastings, with showers blowing into Wellington.

Waka Kotahi system manager Mark Owen said some roads will be very slippery after heavy rain and drivers will need to maintain a safe following distance.

Motorists should make the journey home part of their holiday and take plenty of breaks along the way, Owen said.

Republished by arrangement