At the peak 25,000 homes and businesses were affected but that number has already been reduced to under 12,000.
Technicians are currently trying to restore power to the homes.
“We would ask for customer patience as we safely restore the remaining homes,” Western Power said. “Some customers may take longer that predicted times on the Western Power website if damage is discovered.”
The affects suburbs are: Byford, Armadale, Brookdale, Seville Grove, Bedfordale, Hilbert, Serpentine, Mt Nasura, Mt Richon and Oakford.
If anyone sees a fallen powerline or damage to the network from storms they should make the Safe Call to Western Power on 13 13 51 and stay at least 8 meters away.
Weather forecasters say Perth is set for a very stormy Thursday with up to 10mm of rain expected to fall in parts of the metro area and a chance of a thunderstorm later in the afternoon.