A violent thunderstorm which erupted over Central Hawke's Bay killed more than 50 sheep in an instant when a large macrocarpa tree was struck by lightning and exploded on top of a flock sheltering underneath it.

The century-old macrocarpa tree was struck by a bolt of lightning on Kerry Cheer's farm near Tikokino, during a series of storms in the area about 6.40pm on Friday night.

He said 53 ewes sheltering under the tree at the time were killed on the Smedley Rd property.

"I pulled out just over 30 live ones as well," he said.


"I called a contractor in with a bulldozer to help clean up the mess but it was just an awesome act of nature."

Neighbour Helen Powley was having tea with her husband and watching the storm's beautiful light show when suddenly a "bomb" exploded just 100m from their house.

"Wood was flying everywhere - we saw shards of macrocarpa flying into nearby paddocks. The place just lit up.

"The whole house shook, things fell over, we lost power and the tree started to smoke."

Once the rain had passed her husband and son went to investigate the destruction.

"There were dead and dying stock everywhere. I didn't sleep that well because I was just waiting for the tree to burst into flames, which it didn't do until the morning."

She said she had never witnessed such a display of power before but has been told of similar lightning strikes in the area in previous years.

Mr Cheer said the tree reignited on Saturday morning. The Tikokino and Ongaonga volunteer fire brigades were called to fully extinguish the burning macrocarpa.

Tikokino fire chief Mike Harrison said the "smouldering heap" was "completely obliterated" when he arrived.

"We found pieces of tree 50m to 60m away from the tree. When we got there it was just this smouldering centre of a tree with a number of electrocuted sheep. I've never seen anything like it."

MetService severe weather forecaster Heath Gullery said Hawke's Bay had been struck by lightning about 600 times over the weekend. Sporadic thunderstorms were forecast to continue today.

"Most of these strikes have been in the ranges, where most of the thunderstorm activity has occurred."

He said most of the northeastern North Island had recorded lightning strikes during the weekend.

A MetService severe thunderstorm watch was issued for Hawke's Bay last night which said daytime cloud build-ups are expected to produce scattered heavy showers and thunderstorms about northern, central and eastern parts of the North Island.

"These thunderstorms are expected to be slow-moving and have the potential to be severe, producing localised downpours of 25-40mm per hour and hail," the warning said. "Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips."

The MetService criteria for a severe thunderstorm in New Zealand is rainfall of 25 millimetres per hour, or more, or large hail, 20 millimetres in diameter, or larger and strong wind gusts of at least 110 kilometres per hour.

The local forecast indicates fine settled weather is likely to arrive tomorrow.

The Ministry of Civil Defence and Emergency Management advises that as storms approach people should take shelter, preferably indoors away from windows; avoid sheltering under trees; move cars under cover or away from trees; secure any loose objects around their property; check that drains and gutters are clear; and be ready to slow down or stop, if driving.

During and after the storm, people should also beware of fallen trees and power lines and avoid streams and drains as they pose the danger of flash flooding.