A suspected tornado tore through the WA town of Harvey on Thursday night, damaging roofs and bringing down trees, as a strong cold front battered the state's South West.

Key points: Tornados are not unusual in Harvey and often accompany cold fronts

Tornados are not unusual in Harvey and often accompany cold fronts This one hit about 6:30pm and damaged several houses in the town

This one hit about 6:30pm and damaged several houses in the town Heavy rain was felt across WA's South West, with almost 30mm in Perth

The Department of Emergency Services said it received reports of five incidents related to the event.

The Harvey State Emergency Services (SES) branch attended all of the incidents, one of which Deputy Manager Todd Verrall said brought down trees in the area.

"What they felt was a mini tornado had gone through the northern side of the town and wrecked a few roofs on the way at around 6:30pm last night," he said.

"We headed out to find a road covered in trees that was impassable."

Roof damage in the town 140 kilometres south of Perth was also significant. While no one was injured, the damage resulted in a long night for about 20 of the town's SES volunteers.

Several houses were damaged by the tornado, with part of the roof blown off this property in Harvey. ( ABC News )

"One house there was at least half to two-thirds of the roof on the ground," Mr Verrall said.

"We got the call out at about half past six and my head hit the pillow at around quarter past two, so it was a fairly long evening.

"About 10 years ago we had a bit of twister go through town that damaged eight to nine properties, but this is up there with the worst ones I've seen."

The clean-up begins

Harvey Shire President Tania Jackson said most of the damage was repairable.

"Obviously it's pretty hard when you've got substantial damage to the roof of your home," she said,

"So I think there's going to be some major work, some demolitions probably for sheds, but generally I think they are fixable items."

The Harvey Visitor Centre was damaged after a tree collapsed onto the building during the storm. ( Facebook: Harvey Visitor Centre )

Ms Jackson said the clean-up had a long way to go.

"The council's work crews have been out all day," she said.

"We had SES from Harvey and Australind, fantastic volunteers doing a lot of work last night to secure buildings and clear [roads], but it's a long way to go yet.

"We'll be working on that for a number of days I would think."

Tornadoes accompany cold fronts

The brunt of the impact on Harvey was felt during a 26-minute period beginning about 6:40pm as a result of a cold front moving through the Harvey area.

According to the Bureau of Meteorology, the South West has an average of five tornadoes a year during the cooler months.

Trees were brought down across Harvey as a tornado struck in the middle of a storm. ( Supplied: Beth Ferguson )

Severe weather meteorologist Craig Earle-Spurr said tornadoes that accompanied cold fronts could be hard to predict.

"It can be quite difficult to forecast in advance typically because the front can extend for hundreds of kilometres," he said.

"But the area that might be [affected by a] tornado might only be a few hundred metres.

"So it's always something we're concerned about when we see a cold front coming through, but they are quite rare."

Tornadoes are not unusual in the Harvey area when cold fronts hit. ( Supplied: Beth Ferguson )

Mr Earle-Spurr said it was not possible to measure the wind speeds associated with the damage at Harvey.

"The chance of a tornado hitting one of our actual observation points is so low, so we don't have any significant observations that were reported in terms of the tornado," he said.

"But it was generally gusty across the South West, with winds up to 100 kilometres per hour.

"In general for a tornado we expect to see winds of excess of that."

Heavy rain hits Perth

Much of WA's south-west coast was doused with heavy rain on Thursday night, with 28 millimetres falling in the Perth area to 9:00am Friday, and up to 70mm falling further south.

Harvey was one of the town hardest hit by storms that drenched WA's South West. ( Supplied: BOM )

Winds of up to 94kph were recorded at Rottnest Island last night.

A severe weather warning for Friday night has also been issued for the South West and parts of the Lower West districts.

The Bureau forecasts 100kph winds are possible from 8:00pm onwards, but conditions are expected to ease by Saturday morning.