More than 775 millimetres of rain has been dumped on the Cocos Islands, as residents along Western Australia's north coast prepare for a separate weather system, Tropical Cyclone Rusty.
The downpour on the Cocos Islands, 31 inches in the old scale, was the equivalent of Perth's annual total rainfall in just three days.
The Bureau of Meteorology says the tropical low which brought the rain could develop into a cyclone in the next few days.
Meanwhile, Rusty is expected to cross the West Australian coast some time in the next 48 hours.
The latest bureau advice issued at 5:48am (AWST) said the category two cyclone was estimated to be 315 kilometres north of Port Hedland and 420km west of Broome and was travelling at 4kph.
The advisory says the slow-moving nature of the cyclone makes a coast crossing time and location hard to predict, but there is a high risk Rusty will reach land as a severe tropical cyclone.
A warning has been issued for coastal areas from Broome to Whim Creek, including Port Hedland, with a watch issued for coastal areas from Whim Creek to Mardie, including Karratha and Dampier, and extending inland to Marble Bar and Millstream.
Gales are expected to develop on the coast between Wallal and Whim Creek this morning before extending north towards Broome this afternoon.
Duty forecaster Matt Boterhoven says Rusty could develop into a category four system before crossing near Port Hedland tomorrow night or Wednesday morning.
A blue alert is in place for people in or near the coastal communities of Broome to Whim Creek, including people in or near Port Hedland and Wallal.
The Department of Fire and Emergency Services says while there is no immediate danger, people need to start preparing for dangerous weather and keep up to date.
Emergency authorities say extra crews from the metropolitan area will be deployed to Karratha and Port Hedland today to assist local emergency staff.
State Emergency Service district officer Matt Reimer says staff have also been keeping in contact with remote Aboriginal communities and pastoral stations to ensure they are prepared.
"It's always a risk, especially some of the remote Indigenous communities can often get isolated at this time of the year so we are just checking to see how they are travelling in regards to food stores and fuel and that sort of thing," he said.
"Most of them are fairly good now at preparing themselves, so it's just a bit of a ring-around to check the status of how they are going."
The Port Hedland port has been closed in anticipation of adverse weather.
Apache says it is evacuating non-essential personnel from offshore operations in the area while Woodside says it is taking the necessary precautions to safeguard its people and assets.
The bureau says very heavy rainfall is expected in near coastal parts of the eastern Pilbara and western Kimberley today, with widespread falls tomorrow and Wednesday likely to lead to major flooding in the De Grey catchment.
The bureau says significant flooding in the Fortescue is also likely.
© ABC 2013
17:34 EST The weather bureau's long-term forecast is predicting a drier than normal October to December for much of eastern Australia and north-west Western Australia.