The storm battering the North Island has caused outages across Powerco's electricity networks.

About 800 customers are without power, the majority being in Tauranga (450) and Coromandel (250).

Areas less affected include South Waikato and Taranaki. Extra field crews have been brought in to cope with restoring supply.

Powerco Network Operations Manager Phil Marsh says strong winds began causing damage to the network from around 9pm yesterday.

He says it's difficult to estimate restoration times due to the number of power cuts.

'We are assessing the damage as calls come in. Once we have a better understanding of the extent of repairs needed we can provide more accurate restoration times. We understand this can be frustrating and apologise for the inconvenience.”

'We've had reports of lines down in remote parts of the network and at this stage the weather is preventing getting a helicopter up to inspect the situation."

He says people should take extreme care if they see trees down.

People need to check for downed lines which are dangerous and must be treated as live at all times.

People must keep clear of all downed lines by at least 4m and call emergency services on 111 or Powerco on 0800 27 27 27 immediately they see them.

The storm had struck right in the middle of the school holidays and he urged parents to keep family indoors.

'Trampolines and outdoor furniture become missiles and get tangled in power lines during gale force winds."

Homeowners should take steps to store or tie down backyard gear.

Customers wanting information about power cuts can go to www.powerco.co.nz or call their electricity retailer.

Flooding in Fergusson Park, Tauranga.