Western Power is working to restore services to more than 20,000 properties that lost power overnight.

The outages were caused by pole damage from the humidity and moisture front that passed through the Perth metro area.

“When we have misty and/or humid conditions — generally along the coast or light drizzling rain — this can combine with dust and pollution and create a paths or ‘tracks’ on the insulators which lets electricity jump across,” a Western Power spokeswoman said.

There were around 50 pole top fires.

At the peak of the issue, around 50,000 properties lost power.

At the time of publish, about 22,500 were still without electricity.

As at 7.45am, the most affected suburbs were Thornlie, Canning Vale, Wandi, Trigg and Spearwood.