It might be time to do the seasonal doona switcheroo, because the Bureau of Meteorology is predicting a wintery second half to the week across south-eastern Australia.

“It’s all downhill from here I’m afraid, with rain, wind, snow and thunderstorms all on the way,” said meteorologist Dr Adam Morgan in a severe weather update issued by the bureau on Tuesday.

Maximum temperatures are expected to dip 8 to 14 degrees below the average for this time of year across parts of South Australia, Tasmania, Victoria, Canberra and New South Wales.

“This is a widespread cold outbreak across the south-east on the kind of scale we haven’t seen in April since around 2008,” Dr Morgan said. “It’s going to be cold – really cold.”

For Melburnians, the predicted maximum temperature of 13 degrees on Thursday will make it the coldest April day since 1995.

A top of 7 degrees in Canberra on Friday would mark the earliest below-10-degree temperature in the city since 1952.

And Sydney and Adelaide are expected to reach dreary, though not unprecedented, maximums of 16 the same day.

On Saturday, Melbourne is expected to hit a maximum temperature of 15, Sydney is shooting for 20 and Adelaide can hope for 18 degrees.

Between five and 10 millimetres of rain is expected for some areas, but others can expect far more than that. There may even be snow to 800 metres in Victoria, Tasmania and New South Wales, and frost could reach all the way to the Queensland border.

The good news is things are expected to warm up a tad by early next week. The bad news is it’s autumn and, to invoke the pop-culture cliché, winter is coming.

Watch the full forecast here.