The weather bureau has issued a cyclone watch for Darwin and surrounds.
It says a category one cyclone or monsoon storm is expected to hit the western Top End early on Monday morning.
A tropical low pressure system forming south-east of Bali in the Indian Ocean is heading toward the north Australian coast and is likely to develop into a cyclone over the weekend.
But it is expected to weaken as it heads towards the western Top End.
The bureau has issued a cyclone warning for the Kimberley coastal region of Western Australia between Cockatoo Island and the Mitchell Plateau.
It has declared a cyclone watch for the coast between Mitchell Plateau to the WA-Northern Territory border.
The bureau expects the system to pass over the region early on Sunday morning.
Forecaster Sally Cutter says it will weaken as it heads further east toward the western Top End, south of Darwin, early on Monday morning.
"If it crosses the coast as a cyclone, it is only going to be a very marginal cyclone," he said.
"It may even be below cyclone strength."
The bureau says, regardless, it is likely there will be very strong to gale force winds, with some very heavy rainfall.
Forecaster Briony McPherson says the bureau's three-day tracking map suggests it should weaken in the next few days.
"They [cyclones] can change rapidly but we are keeping a close eye on it," she said.
"I would suggest that people on the western and northern coast of the Territory keep an eye out on our website for the latest information.
"[They should] also start to think about their plans for what they need to do in case of a cyclone."
© ABC 2013
12:35 EST Heavy showers have continued over southwestern parts of Western Australia after yesterday saw some of the heaviest August rain in 100 years.