This in turn “has the potential to lead to widespread flooding” across an already drenched east coast.
“Above-average rainfall also increases the risk of landslides and tree falls in areas of steep terrain and very wet soils,” the BoM said.
There is a high chance of hot nights across the tropical north and in some southern areas, including Tasmania.
Meantime, cooler days are expected for New South Wales, part of southern Queensland and into Victoria.
There is always a bushfire risk in southern Australia in summer, and above-average rainfall can increase the risk of bushfires, the BoM said.
The Summer Bushfire Outlook will be released on November 29.