Residents across New South Wales would have endured an uncomfortable night of sleeping, with many places recording minimum temperatures 8 degrees above average.
Narrabri in the state's northwest only fell to 27.9 degrees overnight, 10 degrees above average and also the towns warmest December night in 7 years. Cessnock in the Hunter only fell to 22.7 degrees, also the warmest December night in 7 years.
People in Sydney would have also felt the heat with the city still 26 degrees at 4am. This was made even more uncomfortable with the humidity sitting close to 70%.
The high overnight temperatures are due to a hot air mass combining with cloud cover, trapping the heat from the hot daytime temperatures experienced across the state.
Central and southern parts of NSW will have some relief today as a cool change moves through the region. However, northern parts of the state can expect another very hot day with temperatures in the high 30's and low 40's, followed by another very warm night.
© Weatherzone 2012
18:16 EST Heavy rain has stranded about 40 people at William Creek in the South Australian outback due to flooded roads and low cloud has grounded aircraft.