UPDATED 12.23pm: A community association's urging calm, amid fears a huge scrub fire at Flock Hill Station could engulf a nearby village.

The blaze has now spread to over three-hundred hectares - with helicopters dropping monsoon buckets of water from the air.

Castle Hill association chair John Reid says it's highly unlikely the blaze could spread as far as resident's homes, but it's proving to be a spectacular sight.

"We can see a lot of smoke. It isn't in the village, really.

"Bit of ash on top of the cars, but that's about it."

Stock evacuated

Stock has been evacuated and emergency plans put in place for residents close to the Flock Hill fire.

The blaze which spread across almost 300 hectares overnight, started in the Craigeburn Forest Park yesterday afternoon.

DOC fire technical support Craig Alexander says volatile weather's making it hard to contain the fire.

"Stock were being evacuated or moved from the paddocks to get them to a safe location because of the changeable behaviour of the fire late last night.

"Emergency evacuation procedures were started for Castle Hill village."

NZTA's urging motorist to avoid the area, advising them to use the Lewis Pass instead.

Meanwhile, Met Service forecaster Paul Melanson says it doesn't look like they'll be much reprieve today.

"No rain, no precipitation expected, so looks like they'll probably have another reasonably difficult day there today."

Fire continues to spread

A fire burning out of control near Arthur's Pass now covers more than 200 hectares.

Alexander says things have cooled down a little bit this morning, but conditions are still dangerous

"Extreme fire behaviour, horrible conditions and unsafe for firefighters on the ground, so it's been attacked in the air using helicopters and fixed wing planes."

Alexander believes State Highway 73 is now fully open, after it was partially closed yesterday afternoon.

However, motorists are still being asked to avoid the area if possible.