The mysterious death of eight dairy cows could be the result of the fierce lightning that hit Masterton.

Kahikatea Te Ore Ore dairy farm manager Bevan Scott found the dead cows at 3am the next day when he went to round up the herd for milking.

"We got through the gate then found one dead, then another one a bit further down and then there was another," he said.

Scott said there was no obvious indication how eight out of a herd of about 420 had died but being struck by lightning was a strong possibility.


Losing the cows was devastating, he said.

He had moved the herd into the paddock so they could take shelter under the trees from the forecasted rain on Wednesday afternoon.

The farm's rain gauge had recorded about 80mm from when the rain began at around 5pm on Wednesday, until early Thursday morning.

"I had never seen rain and lightning like it before.

"It just bucketed down."

One of Scott's neighbours also saw the intense lighting, and the large lumps of hail that remained on the ground until Thursday morning.

Masterton town recorded 42mm of rain in the hour from 5pm to 6pm on Wednesday night – over half the monthly average rainfall for November, NIWA meteorologist Ben Noll said.

"That's pretty significant," he said.


The NIWA weather station at Te Ore Ore recorded 24mm in the same hour.

Noll said the rain was good news for the region as soil moisture levels were very low.

Unsettled weather was expected through to the second week of December, he said.

A Wairarapa Winegrowers Association spokesperson said last Wednesday's hail did not reach South Wairarapa.

Crops were just fruiting and more in danger from a frost than hail or rain, the spokesperson said.