Aucklanders are being warned to prepare for power cuts ahead of predictions the region could see 25mm of rain in an hour - something that hasn't been recorded in three years.
MetService is warning strong winds and heavy rain on Wednesday could cause trees to topple on to powerlines and result in power cuts.
Rain fell steadily in Auckland overnight, causing traffic congestion for Tuesday evening commuters.
The low over the Tasman Sea was expected to hit parts of the North Island from late Tuesday evening and today and could bring thunderstorms and result in flooding in some areas, said MetService.
There are heavy rain warnings in place for the Bay of Plenty and Taranaki north of Eltham with between 80mm and 100mm of rainfall expected to accumulate in the inland areas from 1am to 7pm on Wednesday.
There are also heavy rain watches are in place for the Coromandel Peninsula and the Waikato.
MetService meteorologist Aidan Pysleman said there would be heavy rain in Auckland today and there was also a risk of thunderstorms for the top part of the North Island.
There was also expected to be up to 25mm of rainfall in one hour which would be the biggest fall since April 2017.
Vector has additional response crews and storm management teams on standby, so they are ready respond quickly if required.
Vector head of network field services Marko Simunac said spring weather was very
"So we want to make sure Aucklanders are prepared should outages occur. If
strong winds cause damage to power lines, we'll aim to restore power as quickly as we can, while ensuring the safety of our crews and the public."
Waka Kotahi NZ Transport Agency is also urging Bay of Plenty motorists to stay alert and watch out for surface flooding, slips and fallen trees or branches.
STEPS YOU CAN TAKE TO BE PREPARED
• Always stay away from fallen power lines or damaged electrical equipment.
• Watch out for falling tree branches as these can cause damage to power lines.
• Avoid possible damage to electrical appliances (in the unlikely event there is a power
surge when the power is restored) by switching off appliances at the wall.
• Keep a torch and spare batteries handy and ensure that you have at least one
telephone that does not rely on electricity for operation.
• If you have one, ensure your electric vehicle is charged.
• Ensure that an alternative fuel is always available for cooking (e.g. gas for barbecue).
If you have an electric garage door, prepare how you can gain entry to the garage
another way so you have access to your vehicle.