Residents are being evacuated, houses have been flooded and cars swept away. A witness said this morning it was "absolute chaos" in Kumeu, with all roads in and out blocked by flooding.
"There's one car parked with water up to its windows. There's a stream running off the buildings and footpaths, cars are floating around," he said.
"I've never seen anything like this."
Since Monday evening, numerous locations in the Auckland region have recorded significant rainfall, with localised amounts of an incredible 140-180+ mm observed in western parts of the region.
This has resulted in areas of flooding. Follow advice of local emergency officials. pic.twitter.com/EiTuR6wGHF
Civil Defence has been monitoring the heavy rain and wind since midnight and is warning this morning more people may need to evacuate. A heavy rain watch is in place until 1pm today.
The rain band is expanding into the northwest this morning.
SH16 KUMEU - 6:00AM Due to flooding #SH16 is CLOSED through the Kumeu township (between Matua Rd and Riverhead Rd). Delay your journey until flooding receeds or allow extra time for diversions. Take extra care: https://t.co/tlGvjmsHQg ^TP pic.twitter.com/xZrB5atyx8
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) August 30, 2021
"Remember, do not attempt to drive through floodwaters. If your life or property is at risk, dial 111."
'Houses are underwater'
More than 150 calls about flooding have come in to the fire service overnight - the majority from West Auckland.
A witness told the Herald numerous homes were flooded in and around Birdwood Rd in Swanson and cars were being swept down the road.
"Houses are underwater, cars are flooded and kids are being plucked from their homes in their pyjamas."
The witness said emergency services were out trying to help people and it's understood at least one home was at risk of collapsing.
He saw one man carrying two children through shoulder-height flood water.
Reports of flooding still coming in & the rain band is expanding into the north-west. Remember, do not attempt to drive through floodwaters. If your life or property is at risk, dial 111. Emergency services have been out and about checking those areas most affected. Take care ^Jo
Henderson volunteer firefighters overnight said they were busy dealing with multiple calls to flooding, trees and powerlines that had come down and people trapped by floodwaters.
Roads flooded, trampolines flipped
Residents in and around Kumeu have also reporting flooded roads, backyards and streams that have breached their banks while a family in Whenuapai said the gusts were so strong their trampoline was blown over.
Henderson resident Peter Lee told the Herald he woke up around 12.30am to the sound of his toilet bubbling.
"I thought what the heck is that?"
"I looked out and it [water] was high so I woke up the wife and kids and thought we better get ready to go."
In the time the family was getting to leave their property Lee said the water had risen one meter - and was "crotch deep".
While there wasn't too much damage the carpet was soaked and there were commercial drying machines in there now. The house, which is on higher ground had however escaped the flooding.
"This area is getting hit hard tonight," she said.
Michelle Cawley noticed her backyard had started to flood when her little dog decided to go outside at around 10.30pm.
"I let him outside the ranch slider and he was crying and crying on the deck so I went out there to see what his problem was and I was just like oh my lord."
"I can't even explain it, my family have been here 18 years and this has never happened."
The Taupaki resident said the water was "at least waist high".
"I've seen flooding in different homes and in different streams and creeks."
MetService meteorologist Daniel Corrigan said some parts of West Auckland had recorded close to 90mm of rain in the 12 hours to 1am.
Some areas in Auckland had also recorded 20mm-30mm of rain in an hour.
And, the rain wasn't expected to stop overnight.
"We are expecting to see more rain for most of the day."
The flooding comes after the Auckland region saw about 400 lightning strikes over a roughly three-hour period Monday evening - putting on a light show for two days in a row.
While some areas are more prone to thunder and lightning than others, it's unusual anywhere in New Zealand to see lightning and thunder two days in a row, said MetService forecaster Allister Gorman.
"We usually share them around more," he said.
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Most of the Auckland thunderstorms on Monday were around Helensville and Kaipara Harbour.
"The Auckland area is under a moderate risk of thunder storms until tomorrow morning," but it's unlikely to compare to last night's spectacular show," Gorman said.
The region remains under a heavy rain watch due to a slow-moving front, meaning people should be wary while travelling or if in flood-prone areas. While not all areas will be hit by heavy rain, it remains a possibility.
"There is some uncertainty as to exactly where the heaviest rain will fall, but rainfall amounts may approach warning criteria in the vicinity of this rain-band," MetService has warned on its website.
The thunderstorms are expected to move north towards Cape Reinga on Tuesday, possibly leaving New Zealand by Wednesday, Gorman said.
3.30am | Reports of flooding are still coming in and the rain band is expanding into the north-west. Remember, do not...