Severe thunderstorms with giant hail are forecast for this afternoon and evening in Sydney, the Illawarra and the Blue Mountains and cause flash flooding.

The Bureau of Meteorology (BoM) said there would be storm activity over Accor Stadium between 4pm and 9pm but it would not be severe at that location.

Accor Stadium said the show would only be impacted if the weather was severe.

The severe weather is causing flight cancellations into Sydney, prompting Qantas to fly a plane usually reserved for international travel on a domestic route.

“Due to severe storms forecast to impact the Sydney region late this afternoon, Airservices Australia has limited the number of arrivals and departures in Sydney for all airlines resulting in a number of cancellations and delays,” Qantas said in a statement.

“Qantas will use an Airbus A380 from Melbourne to Sydney to ensure customers get to Sydney as close to schedule as possible.

“The A380 will carry 485 customers, the equivalent of almost three Boeing 737 flights which normally operate this route.”

BoM’s weather warning said there was a high chance of showers late this afternoon and evening.

“A thunderstorm likely during this afternoon and evening, possibly severe with damaging winds, heavy falls and large hail,” it said.

The bureau warned the thunderstorm would hit parts of Wollondilly, Wingecarribee and Greater Wollongong about 2.50pm.

“A severe thunderstorm likely to produce damaging winds, large hailstones and heavy rainfall that may lead to flash flooding was detected near Colo Vale and High Range,” the warning read.

“This thunderstorm is moving towards the southeast. It is forecast to affect Dapto, Lake Avon and Bowral by 3.20pm and Albion Park, Minnamurra and Shellharbour by 3.50pm.”

The State Emergency Service (SES) is warning those travelling to major events to be wary of high winds, damaging hail and heavy rain.

“We may see some very poor weather this afternoon and evening across parts of Sydney, Blue Mountains, Central Coast, Illawarra, parts of the South Coast and eastern parts of the Southern Tablelands,” Chief Superintendent Dallas Burnes said. 

“The weather expected may make things like travelling hazardous, with high end heavy rain and flash flooding a possibility.”

The SES has rostered extra staff to manage the storm.

Will the show go ahead?

Accor Stadium said the show would go ahead rain or shine on its website.

“The only exception would be severe weather which could impact the safety of artists and patrons,” Accor Stadium said.

“Any updates will be communicated to attendees.”

Umbrellas are not permitted into the stadium and rain ponchos are recommended.

Brisbane Airport shows two Jetstar and two Virgin flights heading to Sydney tonight have been cancelled.