A severe weather warning looks set to remain in place for the remainder of Friday as holiday-makers gear up to hit the road for the long weekend.
The warning was issued for residents and travelers across the Peel, South West, Great Southern and Lower West districts on Thursday, with heavy rain and thunderstorms predicted to continue.
Mandurah has seen almost 7mm of rain fall on the city since 9am on Thursday, while Busselton was doused by 15mm in a four-hour span on Friday morning, according to the Bureau of Meteorology.
Other areas affected include Margaret River, Bunbury, Albany, Katanning, Manjimup, Mount Barker, Narrogin and Perth.
Damaging winds are also expected as part of the storm, with gusts averaging 60-70 kilometres per hour.
The Bureau forecasts the storm will ease on Saturday morning.
The Department of Fire and Emergency Services has issued a set of guidelines for road-users who might be making their way south for the long weekend, urging them not to drive into unknown depths of water and to be alert for hazards such as loose debris and fallen power lines.
Drivers should also be sure to keep a safe distance from other vehicles.
The wild weather comes as road safety minister Michelle Roberts announced a new "kindness travels" campaign to coincide with the WA Day long weekend, encouraging drivers to be courteous to one another.
"We all share the roads and if we are to be safe on the roads we all have to get along," she said.
"Please stick to the road rules, don't drive tired or distracted and let's all get home safe this holiday weekend."