January was Australia's hottest month on record, the Bureau of Meteorology says.
The mean temperature last month, averaged across the country, exceeded 30C for the first time ever for any month.
BOM senior climatologist Andrew Watkins said January's heat was unprecedented.
"We saw heatwave conditions affect large parts of the country through most of the month, with records broken for both duration and also individual daily extremes," Dr Watkins said.
A high pressure in the Tasman Sea that blocked cold fronts and cooler air from reaching the country's south, and a delayed monsoon in the north, contributed to the heatwave.
"The warming trend which has seen Australian temperatures increase by more than 1 degree in the last 100 years also contributed to the unusually warm conditions," Dr Watkins said.
For NSW, ACT, Victoria and NT, it was the warmest January on record, while for the other states it was one of their warmest Januaries.