Piha flooding causes evacuations, damage

Piha has taken a hammering. Residents of one street watched as the river quickly rose by metres, and then burst its banks, gushing through their homes as cars floated down the road.

Nearby campers were also caught out. Then the torrent vanished as quickly as it arrived. 

Glenesk Rd reached the brink of disaster in 10 minutes, with everyone taken by surprise. 

Local resident Grant Kerrigan and his family bailed out of their home as the water rose then just as quickly fell - not before two cars were written off and possessions lost.

"You think your house is going to go," he told Newshub . 

There were cars that were moved about 30 metres by the torrent. But in true Piha style on Sunday morning, friends, neighbours and family have all turned up to help people clean up. They provided transport, trailers and helping hands.

Further upstream, Piha Mill Camp turned into a lake, and 60 residents were shipped out to the surf club.

Up in the ranges 20 hikers found nearly all routes out blocked by the rising river.

Tramper Colin Ennor says they hadn't planned for it. 

"We'd packed our sandwiches our towels and our jandals and shorts and next minute we're in the forest for three hours trying to figure out how to get out of here."

The rest of Auckland barely noticed. Here's why. Forty-three millimetres of rain fell in the Waitakere Ranges in one hour, between 5pm and 6pm on Saturday. Compare that to Auckland Airport, where just 15mm fell over 24 hours.

Climate scientist Sam Dean says these downpours have become more common this hot summer.

"We are in a situation that is not normal... and we do know when those sea surface temperatures off the Tasman Sea are higher than normal. That is when we get our heaviest rainfall events."

Piha bore the brunt on Saturday night.