Residents in the flooded West Australian town of Collie are preparing for more rain overnight, after record downpours damaged 40 homes.
The town, 200 kilometres south of Perth, was one of the worst hit areas from unseasonal storms.
A number of homes in the town, which received 126 millimetres of rain in 12 hours on Wednesday, have been evacuated.
Forecasters are warning of more storms across the south-west of the state overnight, while authorities are still trying to restore power to about 1,000 homes.
Shire chief executive Jason Whiteaker says the rain is not easing.
"We're expecting that this level of rain that we're getting now could continue for up to 12 hours," he said.
"So we've got a long night in front of us, I think."
The Department of Fire and Emergency Services (DFES) has issued an alert to let residents know they need to take action, with moderate to major flooding expected in the morning.
The shire says the community is working together to sandbag homes as the Collie River continues to rise.
In excess of 100 millimetres of rain also fell on Harvey in what the Weather Bureau has described as a once-in-a-century event.
The bureau has issued a severe thunderstorm warning that damaging winds and heavy rain are on the way for Perth, Mandurah, Bunbury, Busselton, Margaret River and Bridgetown.
Flood warnings have been issued for the Harvey and Murray river catchment area.
Taken by surprise
The rain follows another storm on Tuesday night, which led to flooding across some parts of Perth, Mandurah and the South West.
The SES responded to more than 100 calls for help.
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.
He 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."
Mr Summerton 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."
The bureau 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," Mr Bennett 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.
"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."
The bureau says the deluge and recent muggy conditions are fulfilling its predictions for the summer season.
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 is mostly on the money.
"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."
There has also been high humidity.
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
14:29 EST Destructive and damaging winds are sweeping across Victoria ahead of a strong front, the Bureau of Meteorology has warned.