Far north braces for drenching as monsoon season grips

Millions of residents in two states are bracing for flooding rains to see out the year as a potentially dangerous monsoon trough threatens Australia's far north.

The event could drench the region with up to 300mm of rain, deliver thunderstorms and trigger flash flooding as the low intensifies across the Northern Territory and into Queensland.

Flood warnings are in place, with severe storms possible across parts of the northeast tropical coast, the northwest and Gulf regions.

For the NT, flood watch warnings have been issued for the Waterhouse and parts of the Barkly, Carpentaria and Arnhem Coastal rivers.

The wild weather marked the arrival of the monsoon season and would be a key concern over the next few days, the Bureau of Meteorology warned.

"There are a couple of key areas to focus on ... across the northwest of Queensland and the North Tropical Coast, these areas are more likely to see moisture converging and more widespread - heavy rain is likely," forecaster Miriam Bradbury said.

"These areas may see well in excess of 300mm or so over the next five to seven days."

The bureau has warned drivers of the risk of road closures and communities being isolated across the remote Queensland outback.

"Flash flooding can occur quickly and quickly cut off roads and access routes across this period between Christmas and New Year," Ms Bradbury said.

"Many people will be travelling or holidaying, so this is definitely something to build into your plans.

"We could see roads closed, roads cut off completely or turned muddy from the rain, and also communities isolated."

The heaviest rain is expected from Saturday into Sunday but may continue into early next week.

While Australia's far north remains in flood watch, bushfires threatening parts of Western Australia southeast of Perth have eased somewhat.

Residents have been allowed to return home, with fires at Boddington and Ranford and surrounding areas downgraded.

Those in Fitzgerald River National Park and along the state's West River were issued prepare-to-leave warnings on Saturday afternoon.

However no homes or properties had been lost.

Boddington residents were earlier warned by firefighters it would not be safe to return to their properties due to unstable conditions.

The Albany Highway also remained impacted by smoke on Saturday.