Residents in the South West town of Collie are continuing the clean up after yesterday's flash flooding.
A number of homes were evacuated and dozens of properties damaged yesterday when a flash flood inundated the town following heavy rain.
Predictions of further rain today fuelled fears of a second round of flash flooding, which didn't eventuate.
However, authorities are closely monitoring the Collie River, which could swell in some areas, as runnoff from the recent rain flows downstream.
Collie River East at Coolangatta is rising and expected to peak later today.
Bureau of Meteorology says areas of localised minor flooding are expected to develop around and downstream of Collie during Thursday and into Friday.
The Rose Road section of the river peaked a minor flood level on Wednesday evening, but that section is now falling.
But Department of Fire and Emergency Services spokesman Chris Widmer says it is unlikely the river will burst its banks.
"Well given the forecast of less than 10 to 15 millimetres of rain over the next six hours with dissipating rainfall tomorrow, we don't believe there's any risk to the Collie River," he said.
"What we will say though, is the river is at a reasonable winter level, and as a consequence it still can be hazardous if people were to enter that."
Mr Widmer says river levels appear to be receding in some areas and it is unlikely more properties will be flooded.
A Bureau of Metereology spokesman says the agency is monitoring storm activity in the Perth area.
"We're not expecting much rain at all in the Collie system today, but there's always the risk that the band of rain [around Perth] could move further south," he said.
People were forced to leave their properties yesterday when flash flooding hit the town of Collie, damaging 40 homes and businesses.
With 127 millimetres falling in just 12 hours, forecasters described the heavy downpour as a 'once-in-a-century' event.
Many have since returned to start cleaning up.
Retail business owner Malcolm Humphreyson worked to get stock off the ground as flash flooding encroached on his electrical shop.
Mr Humphreyson slept in the store overnight to try to save as much as he could.
Residents at a Homeswest complex who were evacuated when flash flooding hit the town, are going home this morning.
The units on Atkinson street were flooded as residents rushed to sandbag doors.
This morning they've returned to find water throughout their homes and swamps in backyards.
In excess of 100 millimetres of rain also fell on Harvey, north-west of Collie.
Cooloongup resident Roy was watching television when the storm broke and flooded part of his house.
"She just crackled wildly, humungous, and the whole power just went off and then about a couple of minutes later she started coming back slowly," he said.
"[There was] water coming down everywhere, right around the edge of the house and all of my electricals, freezers, fridges and televisions."
SES district manager Steve Summerton says Roy's experience is not unusual.
Mr Summerton says the majority of calls for assistance during the storm related to flash flooding.
"Unfortunately the water comes down fairly fast, it rises and goes through doorways into households and disappears just as quick," he said.
"We've also had reports of some roof damage with water leaking in through blocked gutters."
He says if there is one message the community needs to heed this summer, it is to prepare for storms.
"Please get up when its safe to do so, inspect your roofs and make sure you're down pipes and gutters are clear," he said.
"That will stop a lot of the problems occurring with water coming into your house."
Neil Bennett, from the Bureau of Meteorology, says coastal residents south of Geraldton can expect more of the same in the short-term.
"Certainly for parts of the west coast there's a risk of further storm activity this week," he said.
"But then it looks like more normal summer conditions for Perth moving into the weekend."
Longer term, he says it is slightly tougher to call, but he says the deluge and recent muggy conditions are fulfilling its predictions for the summer season.
"It's difficult to say exactly how things are going to pan out for the next few months, but through December already we're looking right on the money," he said.
"We'll just have to wait and see."
Last month, the bureau released its seasonal weather forecast for the months of December to January.
It predicted a hotter and wetter summer than usual for Perth, with above-average rainfall and higher minimum temperatures.
It also gave regional WA a higher-than-normal chance of above-average rainfall.
Mr Bennett says, so far, the forecast has mostly been accurate.
"Certainly with rainfall, we're looking at areas that have already reached above average falls for summer and yet we're only in December," he said.
He says the weather system that created such conditions is not unusual for Perth, nor is the timing.
"We've been saying for the last couple of months that we were expecting above average rainfall," he said.
"But I don't think anybody would have anticipated the amount of rainfall that we saw last night.
"The trough development down the west coast is pretty common, it happens a lot - the unusual aspect of this is actually the length of time we've had it for.
"The system doesn't normally sit around for the amount of time it has, it's usually moving through after one or two days, not three or four."
Perth is known for its hot and dry summer conditions but this week it has been more like the tropics.
"We will always get days when the north-westerly winds come in and produce hot humid conditions for a day or so," Mr Bennett said.
"But what we've had this year is a system that hasn't moved far, so it has kept moist north westerly over the region for longer than normal."
Mr Bennett says the rainfall and humidity can be credited to warmer than average Indian Ocean temperatures.
"We're not looking at El Nino or La Nina conditions here," he said.
"But the Indian Ocean temperatures are a little bit above average and historically that leads to above average rainfall."
© ABC 2012
06:22 EST Parts of Sydney and the Blue Mountains were blanketed by large hailstones after a severe thunderstorm moved across the area this afternoon, causing five warehouses to collapse.