Most parts of NSW and the ACT have sweltered through a second consecutive sweltering night, as thousands head to the beach seeking relief from the heat on Australia Day. Temperatures across most of southeast Australia have spiked over the past three days, with a cool wind change on January 25 delivering milder conditions in South Australia, Tasmania and most of Victoria. But in NSW and the ACT the heat has continued on Australia Day, prompting warnings from health authorities for people to stay hydrated and safe around water. NSW Surf Life Saving chief executive Steve Pearce said beaches along the state’s coast were already packed by 10am on Tuesday, with many nearing capacity. Sunday was a test run for authorities, one of the busiest days in years, with 250 rescues and 750 first aid treatments. With high temps, the big swells, the large crowds, Tuesday will be even bigger, he …