Some 100,000 people were left without power Tuesday after a freak storm battered the Australian city of Perth, hurling golf ball-sized hailstones and causing floods and landslides.

Western Australia premier Colin Barnett estimated a damage bill of hundreds of millions of dollars after the wild weather smashed into the city late on Monday, paralysing flights and commuter traffic.

Thousands of residents jammed emergency phone lines as falling trees downed power cables and crashed into homes in the worst storm seen in years. Hospitals were flooded and some damaged schools remained closed on Tuesday.

"I think from my memory this would be the most severe weather conditions we've had since the famous May storm in 1994, where we had very, very strong winds and a massive loss of power supply," Barnett told public broadcaster ABC.

"Hopefully the damage to the power supply won't be as severe but I suspect this time we've got a lot more damage to buildings and housing."

Nearly 160,000 homes lost power at the height of the storm, which brought wind gusts over 120 kilometres (75 miles) per hour and dumped nearly 40 millimetres (1.6 inches) of rain.

About 20 people were evacuated from one hospital's emergency room after the roof collapsed, while a landslip near the city centre crushed two parked cars and filled one apartment with mud.

Stained-glass windows and glasshouses were shattered at The University of Western Australia, where vice-chancellor Allan Robson said there had been "considerable" damage.

"We were in the eye of the storm, the hail was incredible, the rain was incredible," Robson said.

An "insurance catastrophe" had been declared for the city, the Insurance Council of Australia said.

Cars had their windscreens and back windows smashed by the hailstones, while hazardous driving conditions worsened when 150 sets of traffic lights went blank. Some central office buildings were evacuated for safety reasons.

Further storms are forecast to follow the unusual weather, which comes after Perth's driest southern hemisphere summer on record with just 0.2 millimetres of rain in December, January and February.

On Sunday, a category two cyclone hit the Great Barrier Reef coastline on Australia's east, ripping trees out of the ground and smashing boats and houses.