The state's largest power user, Tomago Aluminum, was on standby to cut back production on Thursday afternoon to help prop up NSW's straining power grid.
The mercury reached 35.1 at Nobbys, 37.7 at Cessnock Airport, 37.5 at Williamtown, 37.2 at Tocal and 37.4 at Lake Macquarie at 2pm as heatwave conditions gripped the Hunter.
