Average temperatures across Australia were greater than 30 degrees Celsius for the first time in recorded history, according to the government’s Bureau of Meteorology.
“We saw heatwave conditions affect large parts of the country through most of the month,” said senior bureau climatologist Andrew Watkins.
The main cause of the persistent heat was a continuous heat-pressure system south of Australia, according to Watkins. The system blocked cold fronts and cold air from reaching the country.
The record month was bolstered by trends in global warming which, “also contributed to the usually warm conditions”, said Watkins.
Meanwhile, in the northern hemisphere, a polar vortex has plunged much of North America into a mind-boggling deep freeze that shut down parts of the Midwest, including in Chicago, with temperatures so far into the negatives that the authorities warned of frostbite within minutes and the risk of eyes freezing shut.
Record-breaking heat wave
Temperatures in Australia have increased by more than one degree Celsius over the last 100 years. And 2018 was Australia’s third-warmest year on record with the average temperature more than one degree above the mean.
The city of Canberra broke temperature records in January with 12 days above 32 degrees Celsius measured at the airport, beating the previous record set in 1947, the Sydney Morning Herald reported.
Rainfall was also below the mean for most of the country, according to the meteorological bureau, worsening a drought in the east of Australia. Only a late January monsoon provided some respite although it brought flooding to the northeast state of Queensland.
South Australia saw the hottest temperatures with the mercury hitting 49.5 degrees Celsius on 24 January.
Impact on wildlife
More than one million fish were killed in the January heat wave, the authorities said, referring to the Murray-Darling river system running through five states in the east of the country.
Dead fish in the Murray-Darling river system
On Monday, Menindee Lakes residents found "a white sheet of dead fish" covering 30km of the Murray-Darling River. Days later, rotting corpses still line the river edge - the stench carrying hundreds of metres into town @SBSNews pic.twitter.com/T5WHoXSL4nMichelle Rimmer (@michellerimmer_) January 11, 2019
High temperatures have been blamed by experts for starving waterways of oxygen, according to the Associated Press. Australian state authorities announced plans to attempt to mechanically pump oxygen into lakes and rivers to help limit the damage.
Bushfires – which are a regular occurrence in Australia’s dry south east – also took hold in the north east of Australia in January.