Authorities have issued a heatwave warning for South Australia ahead of a week of extremely high temperatures. The State Emergency Services (SES) say an indefinite extreme heat warning is in place for the state, with extra crews on alert. The Bureau of Meteorology has forecast temperatures of above 40 degrees Celsius over the next week, barring a ‘cooler’ day of 30 degrees Celsius on 3 February. The heatwave comes as Adelaide hosts the Big Day Out at Bonython Park on 31 January, where some 25,000 people are set to attend. Health officials advise the public to remain hydrated, and remind that police will be on the lookout for suspected drug use.