PENTICTON, B.C. -- Firefighters in British Columbia's southern Okanagan braced on Friday for a change in wind and weather that had the potential to drive a huge wildfire north toward the outskirts of Penticton.

Calm winds over the past few days were forecast to switch direction and gain strength over the 20-square-kilometre wildfire that has already destroyed one home and forced an evacuation order affecting hundreds.

“If we make it through today with the winds being in our favour or just not picking up to quite that same velocity, I think we'll be pretty happy with that,” Nicole Bonnett of the BC Wildfire Service told a news conference. “But fire can be unpredictable just like weather can be unpredictable.”

There were 132 firefighters battling the blaze, assisted by 15 helicopters and other crews, Bonnett said.

The BC Wildfire Service says it was increasing the number of teams capable of setting up sprinkler systems to protect more of the roughly 3,700 homes lying in the possible path of the fire.

Residents of those properties have already been warned to be ready to leave and they've been urged to pre-register with emergency services so officials can prepare for them.

Part of the plan is to use the sprinkler systems to create a humidity bubble, which could stop embers from travelling and starting blazes, Penticton fire Chief Larry Watkinson said.

Penticton Mayor John Vassilaki urged residents to not obstruct fire crews or trucks operating in the city and to co-operate with requests from first responders.

“Now is not the time for looky-loos to be out in the community or stopping their cars to look at the fire,” he said.

The amount of smoke from the blaze led Environment Canada to issue an air-quality warning on Friday afternoon.

In southeastern B.C., a four-square-kilometre wildfire burning west of Canal Flats had exploded to 30 square kilometres in size, but it's not immediately threatening more properties, with 10 remaining on evacuation order.

And residents of a development on Lillooet Lake, north of Vancouver, have been ordered out because heavy rain, coupled with a wildfire on the steep hills above their properties, has the potential to cause a damaging debris flow or cut the only road to the area.

The evacuation order from the Squamish-Lillooet Regional District says there is an “imminent risk” that burned trees and other debris could sweep down McCullock Creek or Catiline Creek just east of Pemberton.

Downpours affecting the Pemberton area were also forecast to drench much of B.C.'s lower south coast, with a heavy downpour warning for Metro Vancouver.

Environment Canada has also issued severe thunderstorm watches for central and northeastern sections of the province.

Strong wind gusts, large hail and heavy rain were in the forecast, with the storm also expected to pack lightning.

However, the wildfire service website showed the risk of forest fires through the Cariboo, Prince George, Stuart-Nechako and Peace River areas was ranked no higher than moderate.

This report by The Canadian Press was first published Aug. 21, 2020