Emergency warnings have been issued for blazes in Perth's south and northeast, with multiple suburbs under threat and people told to evacuate the area if it's safe to do so.
Conditions were "really difficult", WA Department of Fire and Emergency Services Assistant Commissioner Danny Monsconi said.
"We've got wind speeds of around 20 kilometres per hour, but they're gusting up to 50 kilometres," he told ABC Radio on Thursday.
"So pretty challenging."
The wind is expected to change direction later in the day, from the southwest to the east.
There are no confirmed reports of damaged or destroyed properties at this stage, Mr Monsconi said.
The main blaze is burning in the suburbs of Kenwick, Wattle Grove, Maddington and Beckenham.
TV footage from the scene shows several homes in a semi-rural area near the blaze, which is partly burning in a wetlands nature reserve.
Thick plumes of smoke are billowing into the sky, and trees and bush are burning across a broad fire front.
"You are in danger and need to act immediately to survive," an emergency services alert said.
"There is a threat to lives and homes."
Homes are under threat in Bickley Road, Brook Road and Boundary Road, and people should evacuate in a southerly direction if the way is clear.Â
An evacuation centre is open at Maddington Community Centre.
The bushfire is moving in an easterly direction and multiple roads have been closed.
A second fire is burning in Bullsbrook, Upper Swan and Walyunga National Park.
"The alert level for this fire has been upgraded as the fire is still uncontained and uncontrolled," emergency services said.
The blaze is burning in a north-easterly direction, with residents in the area told to leave if it is safe to do so.
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