CANBERRA, Jan. 28 (Xinhua) -- Residents of southeast Australia have been urged to behave sensibly and look after vulnerable friends and family as the region swelters through a heatwave.

The temperature was forecast to hit 35 degrees Celsius in Melbourne on Monday with humidity four or five times higher than the normal level.

Adelaide was expected to hit 39 degrees Celsius while northern parts of Victoria will experience temperatures exceeding 44 degrees.

Paul Holman, Victoria's state health commander, said that people should stay inside where possible and must not leave children or pets in cars.

"We're really concerned for the next 36 hours," he told reporters on Sunday.

Stuart Coombs, a Bureau of Meteorology forecaster, said there was no chance of any relief from the extreme temperature until Monday afternoon.