Dozens of homes have been damaged by a small tornado as Perth experiences wild weather.

Residents of the suburb of Canning Vale say the tornado hit just after 8:00am on Friday and uprooted trees, ripped tiles from roofs and flattened fences.

Resident Jenny Rose Randell says it did not last long but caused extensive damage.

"My house, my fences are down at the front and at the back, I've got a big hole in my roof, one of my trees has been uprooted in the front yard," she said.

"Down the road apparently there's a carport that went through two houses and into a car."

Perth has also been hit with torrential rain that has caused widespread flooding and closed key arterial roads

The weather bureau says 32 millimetres of rain fell Friday morning, which is a third of Perth's rainfall so far this year.

The Bureau of Meteorology says two cold fronts that crossed together Thursday night are responsible for the extreme weather conditions.

The next cold front is expected to cross the coast late next week.