. . . and you thought yesterday was a scorcher Molly Grech, 13, Ben Hutt, 14, and Jazz Bilney, 12, try to beat the heat in Renmark yesterday by leaping into the Murray River as South Australia and Victoria brace for record temperatures. Picture: James Elsby Source: TheAustralian BLISTERING heat in South Australia is threatening to break records, with the fourth day in one of the worst ever heatwaves in the state bringing temperatures of up to 48C. Adelaide is bracing for a record, with the forecast of 46C only 0.1C shy of its hottest day. Along the banks of the Murray River in Renmark, fruit growers and holiday makers are forecast to endure 48C heat, only 0.2C short of the local record. Jazz Bilney, 12, has spent the past three weeks on holiday with her family at a caravan park along the banks of the Murray. "In Ballarat, where we are from, 30C is boiling so we've never really had to deal with this," she said. Melburnians braced for hail and thunderstorms last night before a predicted 44C today. Melbourne reached 41.7C yesterday afternoon, with a minimum of 26C predicted last night. Charlton was Victoria's hottest place, reaching 46.2C, with many towns in the north and northwest forecast to reach 45C today. On Tuesday night, 256 Victorian fires were started by dry lightning, with 15 still going late yesterday. An out-of-control bushfire in the state's northwest was threatening a small number of homes at Yaapeet and Hopetoun West. At Kangaroo Ground, 26km northwest of Melbourne, a grassfire had been contained, with authorities concerned a wind change could force it to cross containment lines, threatening the community of Panton Hill. With the mercury edging 46C in mid-north South Australia, fire service volunteers said there had been more than 300 fires across the state yesterday and on Tuesday; 17 were still going last night. Severe to extreme fire danger conditions will continue today. At least seven firefighters were yesterday taken to hospital suffering heat stress, CFS state co-ordinator Brenton Eden said. "It's going to be a shocker," Mr Eden said. Firefighting equipment was brought in from other states in preparation for the extreme weather conditions, including 25 planes from multiple states and extra firefighting crew from NSW. Power supply operators warned of deliberate cuts to supply in Victoria and South Australia to manage soaring demand. The conditions have seen the highest demand for electricity in Victoria since 2009, forcing the Australian Energy Market Operator to consider reducing the supply to Victoria, potentially affecting 100,000 homes and businesses. SA Power Networks said nearly 3000 homes in South Australia were without power and blackouts across the state could continue today with supply stretched to capacity. With Melbourne expecting 44C today and 42C tomorrow, with wind gusts of up to 100km/h in parts of the state, emergency services are preparing for severe fire conditions. Fire Services Commissioner Craig Lapsley said the fire danger on Friday did not represent the same "code red" risk of February 7, 2009, when 173 people were killed and more than 2000 homes destroyed in Black Saturday bushfires.