September was the driest recorded in Australia since records began in 1900, with a national rainfall average of just 4.83 mm.
The Bureau of Meteorology data on Monday came as fires raged out of control in Victoria and New South Wales amid warnings of possible flooding at the end of the week.
Total rainfall in September was 70.8% below the 1961–1990 average, influenced by the positive Indian Ocean Dipole, the recently announced El Niño and the long-term effects of the climate crisis.
BOM said September – one of the driest months overall since records began – was dominated by high pressure systems, which brought inclement weather and cloudless skies to much of the country.
It was also Australia’s third warmest September on record, with the national average temperature 2.43C above average.
Heat is still high in some states. It was the warmest September recorded in Western Australia and the second warmest in NSW and Victoria. Those three states also recorded their hottest September days on record.
“The high pressure system was the main influence for the hot and dry weather we had across Australia throughout September,” BOM climate science expert Nadine D’Argent said.
The national average maximum temperature was 3.38C above average, the second highest on record for the month of September.
Fires break out in Victoria and NSW as flood warnings are issued
The beginning of October has also brought extreme conditions to most parts of the country.
Three unidentified fires were burning in Victoria on Monday afternoon and parts of the state were warned of possible flooding and damaging winds in the coming days.
In NSW, there were 70 fires burning as of Monday afternoon, 13 of which were not yet under control.
In Tasmania, emergency wildfire warnings were issued for the areas of Mount Tanner and Leeka.
In Victoria, a blanket fire ban was imposed on mallee on Monday due to temperatures above 30C and incoming cold winds.
The BOM said it is expected to cross the state on Tuesday, bringing rain and damaging winds of 90 km/h to 100 km/h across the central and eastern border.
The Country Fire Authority’s chief fire officer, Jason Heffernan, said authorities were anticipating fires affecting the grounds and urged communities to prepare.
“This may mean you may need to take action in the early hours of the morning,” he said. “That frontal system will be in place during the late evening and early morning hours today.”
The BOM said heavy rain forecast on Tuesday could lead to flash flooding, particularly around the eastern ranges.
A low pressure system is then expected to develop over north-eastern Victoria on Wednesday morning and move into eastern Victoria during the day, bringing more rainfall, cooler temperatures, damaging wind gusts and flash flooding, particularly around the Ranges. There is a possibility.
Senior meteorologist Angus Hines said rainfall amounts could reach 100mm to 150mm in some areas over the coming days, with the Gippsland region expected to receive the heaviest rainfall.
He said the slightly cooler conditions in NSW on Monday would be short-lived, with temperatures expected to reach the mid-30s again on Tuesday. In Sydney, the predicted maximum temperature of 33C was about 11C above the October average.
“It will also be very windy,” he said. “This means there will be increased fire danger in many places across NSW.”
Hines said a “surprise change” in conditions would move from Victoria to southern parts of NSW on Wednesday, bringing heavy rainfall to some areas.
He said the low pressure system is expected to move away on Friday, bringing with it rain and winds, but cooler temperatures will continue through the weekend.