It was 50F at the summit and was t-shirt and shorts weather in the crater. One of the popular day hikes is a 12mile trail that starts at the summit (10,020ft), descends down sliding sands and goes through the crater, passing cinder cones, the silversword loop and Holua cabin and campsite at 6940ft, then it ascends up the Halemau’u  trailhead also known as the switchbacks, over rainbow bridge, and ends at the carpark at 8000ft. Weather can change dramatically very quickly, so hikers are advised to prepare well.