'Life-threatening' flooding warning as ex-tropical cyclone heads southeast

There are warnings of life-threatening flooding for parts of New South Wales today as ex-tropical cyclone Kirrily tracks southeast.

Driven by abundant tropical moisture, Kirrily's trajectory is set to bring heavy rainfall to western, central, and southeastern parts of NSW and eastern Victoria today.

The Bureau of Meteorology early today warned the deluge is forecast to bring flash flooding in western parts of the NSW Upper Western district over the coming hours.

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Some areas in the NSW interior may witness accumulations exceeding 200mm by late Wednesday evening, with the bulk of the rainfall expected today and tomorrow.

"Locally intense rainfall which may lead to dangerous and life-threatening flash flooding is also possible," the bureau said.

Locations that may be affected include Tibooburra, Cobar, Bourke, Wilcannia, White Cliffs and Wanaaring.

Meanwhile, the heatwave condition will continue for Sydney and other parts of NSW today.

The top temperature will reach more than 30 degrees across Sydney, but it will be hotter in the western suburbs, where the mercury will climb to 35 degrees or more.

Victoria today is forecast for isolated thunderstorms developing through the north, east and central ranges, local heavy rainfalls are possible in northeastern parts and nearby ranges.

There are strong wind warnings for the Central Gippsland coast and East Gippsland coast.

The impact of ex-tropical cyclone Kirrily is expected to contract to southeastern NSW tomorrow and Wednesday.

The focus will then turn to the flooding risk for the ACT, including Canberra, and densely populated areas south of Sydney.