Firefighters in Australia are facing what authorities are calling the “worst day yet” in an uphill battle against devastating wildfires fueled by soaring temperatures and strong winds. Three fires joined together overnight in the Omeo region of Victoria state to create a 23-square-mile blaze, which is roughly the size of Manhattan. Australia’s Bureau of Meteorology warned that weather conditions were deteriorating rapidly Saturday with winds picking up speed and temperatures increasing to well above 100 degrees. “Today will be a day of severe to extreme fire danger through many districts,” the agency warned. Prime Minister Scott Morrison confirmed Saturday that 23 people had been killed nationwide and more than 1,500 homes have been destroyed since the fire season began in September.