Sydney concert-goers are sweating through a brutally hot day, with temperatures in the 40s, hoping for relief from a cool change sweeping up the east coast.

At least 100,000 people are descending on the entertainment precinct at Homebush, where the mercury climbed to 42C on Saturday afternoon.

US rockers Foo Fighters will play to a huge crowd at Accor Stadium while US rapper 50 Cent is also expected to get thousands of people jumping at his second Sydney show at Qudos Bank Arena, despite the stifling heat.

Thousands more are attending the hard techno dance music festival Epik at the Sydney Showgrounds.

With an earlier start, the dance music fans could miss out on the cool change, but Foo Fighters and 50 Cent fans could be in luck.

The Bureau of Meteorology expected relief to reach the Sydney coast between 6 and 8 pm.

Videos posted to social media show organisers outlining access to cooling station at the Epik event site, with water-misting fans and numerous water stations set up for patrons.

MDMA warning

NSW Health has issued a factsheet urging concertgoers to take a break from dancing if they’re feeling unwell and try to avoid the sun.

It advises fans to take advantage of cool-down stations, and warned the effects of drugs and alcohol are often worsened by extreme heat.

“If you’re dancing, outdoors and or taking MDMA it can be very easy to overheat as the drug interrupts your body’s cooling down mechanism, meaning your body will create more heat than it can get rid of,” the warning read.

NSW Health Minister Ryan Park said the government had been working with the organisers of the events in Western Sydney and was happy with the preparations.

“We’ve worked with organisers to make sure that there is free water available and plenty of water available to those attending those music festivals over the course of the weekend,” he said.

Frontier Touring said extra staff had been hired to help assist with first aid stations set up around the stadium.

The Bureau of Meteorology said the cool change brought relief to South Australia and Victoria overnight, dropping maximum temperatures to the high teens.

The southerly buster is expected to drop temperatures in Sydney by up to 10C, with the bureau also issuing a warning for damaging winds.

-AAP