Motorists travelling between the West Coast and Canterbury today were urged to go through Lewis Pass after an early morning fire at Mount Horrible kept State Highway 73 closed until late morning, when it reopened to single lane.

About five helicopters were being used to tackle the fire on the hillside and close to the road.

The fire was in the vicinity of Coralyn, on the high bluff section of the road as it winds high above the Waimakariri River, between the Bealey Hotel and Cass.

The fire was burning across about 100ha on Mount Horrible but Department of Conservation spokesman Bruce James said it was likely to be under control by early afternoon before a weather change was expected to bring gale force winds.

The blaze is believed to have broken out very early this morning, with the first fire crews on the ground shortly after 2am.

James said the fire was on conservation land and did not pose a threat to people or private property. However, some stock in the path of the fire had been moved out of harm's way.

A staff member from the Bealey Hotel, several kilometres from the fire, told the Greymouth Star late this morning that smoke was clearly visible.

"There's still a lot of smoke up in the gullies," he said.

The highway was "really quiet" this morning although that was not unexpected due to the end of the Christmas-New Year holiday.

"We'd expect to be quiet today for the first time since the end of the silly season."

DoC Arthur's Pass senior ranger Chris Stewart said the village was "pretty quiet" this morning after what had been the busiest recorded period through the visitor centre since 2003, in the past few days.

Traffic was backed up a little in the village this morning, but it was nothing significant given the distance to the fire.

"Businesses are quieter than normal but it seems to be easing back up now," Mr Stewart said.

The New Zealand Transport Agency has reopened the section of SH73 affected by the fire to one-way traffic, with stop-go controllers to let lines of traffic through one at a time.

NZTA media manager Andy Knackstedt said travellers should consider changing their plans, though.

"As an alternative route to the West Coast, we're urging motorists to consider using State highway 7 through the Lewis Pass."

- Greymouth Star