WILLIAMS LAKE, B.C. -- Crews struggling to beat back wildfires in British Columbia braced Friday for the worst as officials predicted weather conditions would deteriorate heading into the weekend.

Kevin Skrepnek of the BC Wildfire Service said the Saturday forecast called for sustained winds between 20 and 40 kilometres an hour across the Cariboo region and the southern Interior, with gusts reaching 70 km-h in some areas affected by the fires.

"That level of wind certainly has the prospect to really whip up fire behaviour," Skrepnek said. "If that forecast comes to fruition, it's going to be a big challenge for us.

"We could be seeing some pretty extreme and aggressive conditions."

About 170 wildfires were burning across the province's central and southern Interior, including three around Williams Lake, where 11,000 people were on standby to leave their homes.

Since the fire season began in April, more than 616 blazes have consumed 1,140 square kilometres of land, forcing officials to order evacuations affecting 16,680 people.

Rob Turner, assistant deputy minister for Emergency Management B.C., said some 4,000 families had registered with Canadian Red Cross as of Friday afternoon. More than 10,000 people had registered at reception centres, about half of whom were being housed in group lodging.

Prime Minister Justin Trudeau announced the creation of a new ad hoc cabinet committee to co-ordinate the federal government's response to the fires, including recovery and rebuilding efforts. The committee includes the ministers of justice, national defence, indigenous and northern affairs, and public safety and emergency preparedness.

Al Richmond, chairman of the Cariboo Regional District, said there was a noticeable difference in the air quality when he went to Prince George on Thursday night.

"It was refreshing for me to get into Prince George ... and breathe the fresh air instead of the smoke-filled air we are experiencing here in the Cariboo," he said on Friday.

Richmond said he told a meeting of evacuees on Thursday night that efforts were underway to restore some normality in fire-weary communities.

Regional district offices in Quesnel were slated to open Friday to provide permits allowing workers to travel on closed roads to reach the open pit copper-molybdenum mine operated by Taseko Mines Ltd.

The provincial government has also been asked to allow some movement on closed sections of Highway 97 so that people who left their homes in Williams Lake and went to Prince George could drive south to Vancouver.

The province declared a state of emergency last week and more than 16,000 people have been affected by evacuation orders, with thousands more on alert.

The province said evacuees must remain patient and wait for official notice before they can return home. It has also warned that violating orders can divert firefighters from fires to help with avoidable rescues.

Fire crews have been able to oversee significant controlled burning over the past few days around Williams Lake thanks to a brief reprieve in the weather, Skrepnek said.

"We've been conducting some really aggressive controlled burns out there, basically back-fires, to remove the fuel, burn it out now before the fire has the chance to spread," he said,

Skrepnek said more burns were planned for fires around Williams Lake, 150 Mile House and Ashcroft.