The massive Canterbury blaze that caused multiple evacuations has nearly doubled in size overnight to about 980ha.

A main highway that the fire roared on either side of has now reopened after efforts to extinguish the blaze today; with a speed limit of 50km/h imposed on motorists using the route.

But, Incident Commander Brian Keown says the fire is still not contained or controlled.

Fire and Emergency New Zealand district commander Dave Stackhouse said a total 86 firefighters were on the ground battling the blaze.

Holloway Lodge - an old Fire Service Hut - had been destroyed.

The focus of firefighters over the next few days would be to secure the perimeter of the fire.

“We’ll maintain the helicopter presence and probably reduce the fixed-wing assets over the next 24 hours,” Stackhouse said.

Stackhouse said a lot of the “heavy fuel” growth in the area had been extinguished.

He added fire officials had a “reasonably good indicator of the fire’s cause”. Fire investigators and police were working on the cause which Stackhouse said was a “normal” process.

He also confirmed that Canterbury would be going into a restricted fire season.

“The high country we’ve been watching is pretty dry.

“It’s likely before Christmas we’ll move to a prohibited fire season, which means no burning at all.”

Fresh firefighting crews would be rotated onto duty to battle the fire over the weekend.

Many of those involved are volunteer firefighters.

Earlier, smoke from the Bridge Hill fire drifted towards Castle Hill Village, and there were fears that flames could follow.

However, Keown said the fire did not enter the village overnight.

SH73 has now reopened this afternoon after being closed due to the fire.

Fourteen Castle Hill Village residents have self-evacuated along with several school camps and lodges.

Forecasters say winds have picked up slightly but changed direction - Keown said the weather conditions are “favourable for firefighting”.

“The wind is not as strong as it was yesterday and there is some rain forecast for the area in the afternoon which, if it eventuates, will aid our efforts to contain the fire,” Keown said

Keown said 15 trucks, tankers and support vehicles were on the ground this morning while nine helicopters and three fixed-wing aircraft prepared to fight the fire.

There are also crews working with heavy machinery on the ground.

“Crews are also continuing to protect huts and other structures in the area.”

There are 85 Fire and Emergency NZ personnel on site today, including an Incident Management Team and the Region Co-ordination Centre back in Christchurch.

Fire and Emergency said any reopening will involve traffic restrictions.

There will be a community meeting for impacted residents at 1pm at the Tawera Memorial Hall in Springfield.

Keown told TVNZ’s Breakfast they did not anticipate any evacuations today.

He said crews worked overnight on SH73, battling the fire on either side of the road.

They hoped to have the fire contained by the end of the day and fire investigators would start examining the cause.

The fire on Bridge Hill has reached 140ha in size. Photo / Fire and Emergency New Zealand

MetService meteorologist Brian Mercer said the wind direction changed overnight to southwest.

He said wind gusts up to about 50km/h were expected today with mid-20s temperatures.

He said winds will be “relatively strong” in elevated areas until the evening when it dies down slightly. He said there are a few showers forecast for the evening about the Canterbury plains.

Diversions are in place on State Highway 73 at Castle Hill Village, Arthur’s Pass, and Springfield near Annavale Rd.

Fire and Emergency services on the scene of the Bridge Hill wildfire. Photo / Fire and Emergency

Motorists are advised to avoid the area.

Keown says students from three schools were evacuated from camps in the area as a precaution. Students from two of the schools had been staying at the Environmental Education Centre, while the others were at Forest Lodge.

“All other school camps are safe and away from the fire.

“Parents can be assured that their children are not in danger.”

Rudolf Steiner School principal Paul Kennedy told the Herald a group of its students were evacuated from the Environmental Education Centre.

“They were transported back to school. We are very thankful that all our students, staff and helpers are safely back home,” he said.

The large vegetation fire on Bridge Hill in central Canterbury. Photo / Fire & Emergency

Health New Zealand Te Whatu Ora issued a public health warning for the smoke from the Bridge Hill fire.

“Air around this location is smoky and there is potential that people who are sensitive to smoke – such as those with heart or lung conditions, people who are pregnant, young children and the elderly – may experience symptoms like coughing, shortness of breath or eye, nose and throat irritation,” it said in a statement.

Fire and Emergency services hope to have the fire under control by the end of the day. Photo / NZTA