Updated 9.17pm: A man has been killed by a falling tree in Northland.

The incident happened during bad weather in the settlement of Tinopai East of Dargaville.

Fire service and a helicopter were sent to the scene but the man wasn't able to be saved.

Earlier today lightning struck Dargaville Hospital.

The Fire Service was called to the hospital earlier this afternoon.

Windows were reportedly blown out by the strike, and an alarm was triggered.

Dargaville Volunteer Fire Brigade spokesman Brian Klume says its lucky nobody was hurt by the flying glass.

"The only problem would have been if someone was walking down the hallway when the glass got broken, because it came inside."

He says emergency generators kicked and the wellbeing of patients was not threatened.

Thunderstorms are lighting up the skies in western Auckland.

WeatherWatch says lightning and thunder have been going nonstop since about 4:30pm.

MetService has issued a severe thunderstorm warning for the region.

It says its radar has detected thunderstorms on the west coast - including Muriwai Beach, Helensville and Woodhill.

The power's still out in Auckland's Belmont - now to around 600 homes.

But more than 600 homes have had supply restored in Dairy Flat north of the city.

Vector's Sandy Hodge says its because of rough winds, rather than the lightning strikes across the city.

"It's been vegetation dropping it on to lines, and that's wind carrying wet vegetation."

Its website says it should be restored around 7:40pm.

The thunderstorms will track southeast tonight.

The storm has hit also New Plymouth.

Loud bursts of thunder have echoed around the city, and heavy rain has begun to fall.