A total fire ban is in place for parts of NSW as a heatwave that has gripped much of the state starts to wane while soaring temperatures in South Australia give way to flooding rain.

Temperatures climbed into the low to mid 40Cs across central western and coastal parts of NSW on Saturday before a strong southerly buster swept up the coast, bringing thunderstorms and dropping temperatures by up to 10C.

The strong winds caused damage to several homes on the Central Coast, with roofs ripped off during a short but strong storm burst.

The RFS was battling at least 70 fires across the state, with several uncontained by Saturday evening.

Warm temperatures will continue into Sunday.

Tens of thousands of people sweated it out at several concerts at Homebush in Sydney’s west on Saturday, with the mercury climbing to 43C before a southerly change swept through after 6pm.

Extra staff were on hand to help those overwhelmed by the heat at separate concerts by the Foo Fighters and 50 Cent and the hard techno music festival Epik.

Severe weather warnings were issued for NSW late on Saturday for strong winds and thunderstorms with possible large hail as the cool change made its way up the east coast.

In South Australia, a severe weather warning was issued for the Eyre Peninsula, West Coast, and North West Pastoral districts for heavy rainfall on Sunday.

Angus Hines, from the Bureau of Meteorology, said a long band of rain stretching from eastern Victoria across southern SA up towards the northwest had prompted the major rain warnings.

“The southern part of central SA becomes the focus point for quite heavy rain on Sunday – persistent falls, pretty much all day,” he said.

As much as 100m of rain could fall over the eastern part of the Eyre Peninsular – well more than December averages of 15mm to 30mm.

“So, for a lot of places, this weekend will represent two months of rainfall, if not more than that, for this time of year,” Mr Hines said.

Victoria, Tasmania, the far south of NSW and parts of the Northern Territory can also expect high rainfall totals across the weekend.