About 200 sheep died on one property at Captain's Flat, in south-east New South Wales, this week, from exposure to cold weather and rain.

The sheep were shorn the day before up to 100 millimetres of rain fell in the area.

Braidwood district vet for the Livestock Health and Pest Authority, Doctor Bob Templeton, says the farmer involved is devastated.

"The rain and the wind came on and the rain just didn't stop and the sheep, about lunch time, started getting really really slow," he said.

"And so the farmer decided he better put them into shelter, but they didn't want to move, and then some of them started to die and when they got into shelter they continued to die."