Cold front to bring cooler weather to eastern Australia

After a warm start to spring, temperatures are forecast to plummet across Australia's eastern and south-eastern states in the coming days.

"We are expecting a significant change to come for much of the east and south-east of the country," the Bureau of Meteorology's Jonathan How said, with New South Wales, Victoria, Tasmania, South Australia and Brisbane forecast to experience cooler weather in the coming days.

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BoM meteorologist Miriam Bradbury said heavy rain, storms and flooding would continue in Western Australia, the Northern Territory and SA on Tuesday before moving to the eastern states on Thursday.

In Sydney the temperature is expected to plunge by 12C from a maximum on Wednesday of 31C to about 19C to 20C on Thursday and Friday.

How said Sydney's weather had gotten a "really warm run", with the city recording maximum temperatures above 25C since last Wednesday.

The average maximum temperature for Sydney at this time of year is 20C, the meteorologist said, so "the fact we're getting at least five degrees above average is quite significant".

"For Sydney in particular, it'll be quite a contrast from walk-on-the-beach weather to quite cool and rainy weather on Thursday," he said.

By then eastern NSW would be the wettest part of the country, How said. The BoM has forecast that Sydney will receive 10mm to 40mm of rain on Thursday but some areas, including the Illawarra, Wollongong and the southern tablelands are expected receive more than that, with showers continuing into Friday.

The weather forecasts provider WeatherZone has reported that more than 200mm of rain will fall before the end of the week, enough rain to cause flash flooding. It flags the possibility of snow in parts of southern and central NSW, and even parts of the central tablelands, with damaging winds in some areas.

In Melbourne the temperature is expected to fall from a maximum of 23C on Tuesday to 14C on Thursday and 15C on Friday.

Brisbane's temperature is also forecast to drop to a maximum of about 22C to 23C on Friday, from 29C on Thursday.

Hobart and Adelaide are expected to see smaller shifts in temperatures.

In Adelaide maximum temperatures are forecast to drop slightly from 22C on Tuesday to 18C to 19C on Wednesday and Thursday.

The BoM is forecasting maximum temperatures of 13C to 14C in the Tasmanian capital on Wednesday and Thursday, from a maximum of 17C on Tuesday.

How said southern Tasmania could expect up to 300mm of snow in the coming days, with a few flurries forecast for parts of NSW and Victoria .

The cool change was due to the effects of a rain band moving across central Australia and a cold front coming through on Tuesday night, he said.

Showers in Melbourne, South Australia and Hobart were likely to ease on Thursday morning, he said, with the weather in Sydney drying up late Friday to Saturday.

The weather was expected to warm up on Saturday, just in time for the AFL grand final, but more showers were expected early next week.