Melbourne, where the tournament is held, is seeing a third consecutive day of heat above 40C, with temperatures of 41.7C (107F) on Thursday.Australia's Climate Council says in a report that the number of hot days in the country has "more than doubled".2013 was recently declared Australia's hottest year on record.Australian Open organisers said their extreme heat policy was in force, with matches being suspended at the end of their sets."Play will not resume on outside courts until at least 1700 local time (0600 GMT). Matches at Rod Laver Arena and Hisense Arena will continue with a closed roof," organisers said in a statement.Tournament officials say temperature, wind direction and humidity are taken into account when implementing the extreme heat policy.'A thousand fires'The announcement came mid-afternoon with the hottest part of the day approaching, the BBC's Jon Donnison in Melbourne reports.On Tuesday, a tennis player and a ball boy fainted in the heat during the tournament. Organisers were criticised for allowing the tournament to continue.Melbourne resident James Hickey told the BBC: "The past couple of nights have been insanely hot.""In my suburb of Brunswick we lost power for about three hours on Tuesday night because it was so hot. The traffic lights were out, nobody could run their air conditioning or watch TV."Meanwhile, an interim report from the Climate Council said the number of heatwaves in Australia was "projected to increase significantly.""Both the duration and frequency of heatwaves" had increased between 1971 and 2008, it said."As greenhouse gases continue to accumulate in the atmosphere from the burning of fossil fuels, more heat is trapped in the lower atmosphere," the report added."This increases the likelihood that hot weather will occur and that heatwaves will become longer and more intense."In the South Australian capital, Adelaide, temperatures were forecast to reach 46C, nearing the city's record of 46.1C.Fire bans are in place across the states of Victoria and South Australia, with several fire alerts in place.Victoria Fire Services Commissioner Craig Lapsley said: "A thousand fires have been reported over the past 24 hours and 39 of those are still listed as going."On Tuesday night, lightning strikes sparked more than 250 fires in the state, fire authorities said.Earlier on Thursday, South Australia fire services co-ordinator Leigh Miller said some firefighters had started to develop "heat exhaustion-type issues"."Fighting fires in 40 odd degrees weather with little sleep is a real problem for us."Forecasters say the extreme heat in much of south-eastern Australia is not expected to ease until the weekend, the BBC's Jon Donnison reports.(BBC)ANN.Az