Record-breaking warm temperatures for the start of May in many parts of the country will be washed out by a cold front bringing rain, thunderstorms and much cooler weather.

A high-pressure system dragged warm northerly winds across south-east Australia, the Bureau of Meteorology (BoM) said.

Daytime temperatures on Friday were 10 to 14C above average in parts of New South Wales, Victoria, South Australia and Tasmania, while dozen of stations recorded their warmest May day on record.

In Victoria, Geelong, Shepparton and Bendigo were among the places that had the warmest days on record with temperatures in the high 20s, while in Tasmania, records were toppled in places including Hobart and Launceston, which recorded 26.9C and 24.3C respectively.

Night-time temperatures across parts of South Australia, Queensland, Victoria, Tasmania and NSW were eight to 12C above average on Friday night.

Australia has also had its driest April since 2018.

A cold front over the Southern Ocean, which circles Antarctica, merged with a cloud band moving over Western Australia to form the cold front which swept across South Australia on Saturday, heading towards Victoria and Tasmania.

BoM meteorologist Christie Johnson said on Friday that there had been “unseasonably warm conditions over the last couple of weeks”.

“However, as we move into Sunday, we do see that cooler air extending across SA and into western Victoria, with maximum temperatures dropping just back into the high teens,” she said.

“And finally on Monday, the cold air will make its way right across the south-east, with much cooler temperatures.

“And this will feel particularly cool … given the warm temperatures we’ve had recently.”

Thunderstorms, rain, windy conditions and “abnormally high tides” were expected over south-eastern Australia over the weekend and into the start of next week.

There is a risk of severe storms, heavy rainfall and potentially flash flooding, she said.

Sydney will be spared the wintry blast, though, with temperatures forecast to remain in the mid-20s most of the week.

Sydney’s maximum temperature is expected to reach 26C on Sunday, with rain and 25C predicted for Monday. Rain is forecast for Melbourne all week, with a maximum of 23C on Sunday dropping to 13C by Thursday.