While many Wairarapa vineyards dodged last Friday's unusual frost, a few pockets were hit hard.

Up to 50 per cent of some vineyards' crop may be lost due to a rare type of frost that hasn't been seen in the area since 2006.

The region's vineyards were assessing the damage after some of the usual mitigation measures failed.

Viticulturist Nick Hoskins said he had visited a range of wineries and the damage varied at each one.

One of the worst affected areas was on Te Muna Rd south east of Martinborough.

"There will be some crop loss. How big that is, I don't really know.

"Even though they are quite severely affected, you can see green shoots across all blocks. Could be up to 50 per cent [loss at the worst affected," he said.

Friday's weather event appeared to be a rare advection frost which was a mass of cold air without an inversion layer, Hoskins said.

Vineyards would normally use frost fans to pull the warmer air from the inversion layer to blow over the vines and prevent frost settling.

The good news was that after the 2006 advection frost, the quality of the 2007 vintage was not adversely affected.

"We survived that alright. Certainly yields were down, but there were no quality issues," he said.

Katherine Jacobs of Big Sky Wines on Te Muna Rd said they were assessing its losses, but accepted that frosts were part of the risk of growing good pinot noir.

They have watered the vines and were waiting to see what plants will regenerate.

"They are amazingly resilient. We will be getting some crop, we are just not really quite sure how much will come back."

Central and northern Wairarapa wineries were also hit by the rare frost.

Karl Johner of Johner Estate in Carterton believes he lost 20to 30 per cent of his crop.

"It really kicks you in the butt. You can pay a lot of wages with that if you end up making it into wine."

He estimates he lost five of his 16 hectares of crops. His Masterton block was wiped out because it had no frost protection at all.

John McNab of Carterton's Fairmont Estate said they may have lost up to five per cent of their crop, but it was a loss they could weather.

"It's just farming. Typically up to the end of November you can expect the odd frost, so we're not out of the woods."

Alastair Scott of Matahiwi Estate vineyard north of Masterton said the fall of their landscape meant the cold air did not settle on its vines and escaped frost damage.

Wairarapa Winegrowers Association refused to comment on the damage from last week's frost other than to say vineyards were still being assessed.