Heavy rain and high winds are battering the region as severe thunderstorms make their way down the North Island.

MetService has issued a heavy rain warning for Bay of Plenty, west of Ōpōtiki, until midnight tonight.

Emergency Management Bay of Plenty spokeswoman Lisa Glass said all the region's council and civil defence emergency management duty staff were aware of the weather and keeping a "close watch" on it as it approached.

She said people should check on emergency supplies and have a 'grab bag' of essentials handy in case they need to evacuate.

And even those infected with Covid-19 should evacuate if needed, she said.

"People should follow Covid protocols as much as possible, but don't let anything slow you down if you need to get out."

Bay of Plenty Civil Defence has issued several advisories and Powerco has reported several power outages in the Western Bay of Plenty with hundreds of customers without power in Greerton, Matapihi and Aongatete.

A Northern Communications Fire Service spokesman said powerlines were down on Maleme St in Greerton. One fire crew were on scene keeping the area safe until Powerco staff arrived, he said.

Meanwhile, a trampoline had gone across powerlines on Leander St in Mount Maunganui.
The spokesman said crew was at the scene waiting for Powerco staff to remove the trampoline.

Thames Coromandel Civil Defence controller Garry Towler is urging everyone to take extra care over the next 12 hours while the storm passes over.

"Avoid being outside, secure loose objects around your property, avoid non-essential travel, have batteries and torches on hand and just hunker down somewhere safe for the afternoon and evening.

"This is a fast-moving convection storm. It is unpredictable and difficult to accurately forecast, so err on the side of caution and avoid any risks until it's safe."

Bay of Plenty can expect 80 to 110mm of rain with peak rates of 15 to 40mm/h especially during thunderstorms. Another period of heavy rain is likely for the area on Tuesday.

Heavy rain warnings and severe thunderstorm watches are also in place for the Coromandel Peninsula.

Such storms bring torrential rain that can cause flash flooding and slips. People should take shelter indoors and away from trees when they approach, MetService says.

Localised tornadoes are also possible and could cause damage to trees and powerlines.

A heavy rain watch is also in place for Taupō with possible thunderstorms.

Take shelter, stop driving: Emergency advice in thunderstorms

MetService pointed people to advice from the National Emergency Management Agency, which said when storms approached they should take shelter indoors away from windows and avoid standing under trees.

They should get off the water, move cars under cover or away from trees, check drains and gutters were clear and be ready to slow or stop driving.

During and after the storm, you should also beware of fallen trees and power lines, it says.

"Avoid streams and drains as you may be swept away in flash flooding."

The line of thunderstorms were first spotted offshore as it approached the Bay of Islands just after 1am, and has been moving south through the small hours of the morning.

Credit: NZHerald.co.nz