Nullarbor has had its hottest pair of December days in five years, ushering an extremely hot air mass into South Australia. The town reached 41 degrees on Tuesday and today, the first time this sort of heat has been strung over two December days since 2007. Northerly winds sweeping across South Australia over the next few days will carry this heat towards Adelaide, ensuring a sweltering end to the first week of school holidays. Adelaide is forecast to reach at least 38 degrees for the next three days, peaking on Thursday as the mercury heads for the low forties. It has been five years since the city has experienced a three-day run as hot during December. Relief for the capital will arrive on Friday after a southerly change moves through late morning or early afternoon. Initially it will remain noticeably warm behind the change into the late afternoon, however a cooler air mass will arrive during the evening. Thankfully for parents and children alike, Sunday will be far more bearable with a maximum temperature more than 15 degrees cooler than Thursday.