As stormy weather continues to batter the country, one small town in the North Island has been devastated by flooding.

Kaiaua, on the Firth of Thames, was submerged by fast moving waters with a sea surge racing 300 metres inland in only 30 minutes.

The flood was brought on by a high tide around 11 am which struck both sides of the Firth. 

The suddenness of the flood took people completely by surprise, with many coastal buildings flooded.

Barbara Campbell, a St John first responder in the town, said nothing can be done until the water subsides.

"I hate to say, it's just everyone's in a bit of a daze. People are just standing out on the street just looking, not really knowing what to do really."

She said that big trees are lying all over the roads. 

"They've got the grader working now because the beaches come up onto the road, all the sand and shells. I've got on my front doorstep, I've got jellyfish."

The flooding caused damage on a road between Thames and Manaia, which closed due to slips and fock falls. 

The New Zealand Defence Force and Red Cross are in the area to help stranded and evacuated people.

Thames-Coromandel District Council Civil Defence Controller Garry Towler said if people need assistance or any help, to call 07 868 0200.

He's urging people to take care saying the region's not out of the woods yet.

An evacuation centre was opened at the Te Puru community hall, 12 kilometres north of Thames, for stranded residents and motorists forced to leave their homes. 

Towler said once the tide has completed subsided, they will know how best to help those in remote areas. 

"Our major issue is in welfare and just making sure that the people who have been affected by this big tide and have had their homes damaged or inundated, we just need to make sure they are okay."

People in Pauanui have been urged to conserve water as the Thames-Coromandel Regional Council had to stop the flow of water to the community.

"The Pauanui Water Treatment Plant is not operating and it has been shut down simply due to the debris and turbidity in the river that surprised that plant," Towler told reporters.

Towler said the water treatment plant's likely to stay shut for 24 hours, until the river clears and clear water can run through again.