Firefighters are bracing for extreme fire weather conditions today as they fight an expanded fire ground at a large blaze in the shires of Gingin and Dandaragan.
An emergency warning was expanded overnight to include parts of Regans Ford and Yathroo after the fire broke containment lines north of Regans Ford.
The fire jumped Brand Highway, leading to sections of the major route in and out of the metropolitan area being closed.
Brand Highway is now closed in the areas of Gingin, Badgingarra and Cataby and motorists are being told to avoid the area.
The fire has been burning since Saturday and has already razed 9,900 hectares of bushland and pine plantations, in conditions not seen for two to three years.
Temperatures in excess of 40 degrees Celsius are expected in the area today, with north-easterly winds gusting up to 40 kilometres per hour, testing containment lines.
Hundreds of residents, many from the coastal communities of Ocean Farms Estate and Seaview Park Estate, have already evacuated.
A community meeting will be held later this morning in Guilderton.
Yesterday another fire escalated about 80 kilometres south of the main blaze, in the Yeal Nature Reserve and Yanchep Pine Plantation.
It escalated quickly, burning through another 2,000 hectares.