Firefighters battling a major bushfire north of Perth are bracing for their "last big test" as crews start to get the upper hand on the 10,000-hectare blaze.
An emergency warning has been in place for the Red Gully fire for several days with the flames coming within one kilometre of the Ocean Farms housing estate at one stage.
The warning level was reduced to a watch and act on Friday, despite the ongoing hot and dry conditions.
Incident controller Superintendent Sven Andersen said there was still much work to be done by crews on the fire ground and efforts to completely control the fire would likely continue for the next five days.
But he said he was quietly confident heading into the weekend.
"I'm not expecting it to get much bigger," he said.
"This afternoon will probably be our last big test.
"Tomorrow is a concern, but if we can hold it on these south-westerly winds today I think we're in a good position."
About 150 firefighters remain on the scene involved in mopping up and strengthening containment lines with aerial support still being deployed.
The fire has blackened 10,230 hectares inside a perimeter of about 140 kilometres after burning since last Saturday.
There have been no reports of major property losses.
Residents from the affected areas are being allowed to return to their home but have been urged to remain vigilant.
Temperatures across WA's southwest soared into the 40s on Friday, but were expected to be marginally cooler on Saturday and cooler again on Sunday.
A sea breeze had also helped fire containment efforts along with a rise in humidity.
The cause of the blaze is yet to be determined.
Supt Andersen said the main concern over the coming days was for the northern flank of the fire where it was burning close to a highway and a major transmission line.
That line tripped at one stage on Thursday but came back online almost immediately.