Australia records driest September as fires rage in NSW, Victoria and Tasmania | Australia weather

Australia has recorded its driest September since records began in 1900 with a national rainfall average of just 4.83mm.

The data from the Bureau of Meteorology on Monday came as fires burned out of control in Victoria and New South Wales amid warnings of potential flash flooding later in the week.

Total rainfall was 70.8% below the 1961-1990 average for September, influenced by a positive Indian Ocean dipole, the recently declared El Niño and the long-term effects of the climate crisis.

The BoM said September – also one of the driest months overall since records began – was dominated by high-pressure systems that brought settled weather conditions and cloudless sky for most of the country.

It was also Australia’s third-warmest September on record, with a national mean temperature 2.43C above average.

In some states, the heat pushed higher still. Western Australia recorded its warmest September on record and NSW and Victoria their second warmest. Those three states also recorded their hottest September days on record.

“The high-pressure systems were the main influence for our warm and dry weather across Australia throughout September,” the BoM climatology specialist Nadine D’Argent said.

The mean maximum temperature nationally was 3.38C above average, the second-highest on record for the month of September.

Fires burn as flood warnings issued

The start of October has also brought extreme conditions across much of the country.

Three uncontained fires were burning in Victoria on Monday afternoon and parts of the state were warned of potential floods and damaging winds in coming days.

In NSW, there were 70 fires burning with 13 yet to be controlled as of Monday afternoon.

In Tasmania, a bushfire emergency warning was issued for Pine Scrub and Leeka on Flinders Island.

In Victoria, temperatures above 30C and winds from an approaching cold front prompted a total fire ban in Mallee on Monday.

The front was expected to cross the state on Tuesday, bringing rain and damaging wind gusts of 90km/h to 100km/h through the central and eastern ranges, the BoM said.

The Country Fire Authority chief fire officer, Jason Heffernan, said authorities were expecting the front to affect fire grounds and urged communities to prepare.

“That may mean you may need to take action in the very early hours of the morning,” he said. “That frontal system will come into effect late this evening and into the early hours of the morning.”

The BoM said heavy rainfall forecast for Tuesday could deliver flash flooding, particularly around the eastern ranges.

A low-pressure system was then expected to develop in north-eastern Victoria on Wednesday morning and move into eastern Victoria during the day, bringing more rainfall, colder temperatures, damaging wind gusts and the potential for flash flooding, particularly around the ranges.

Senior meteorologist Angus Hines said the amount of rainfall in the coming days could reach 100mm to 150mm in some areas, with the highest totals expected in the Gippsland region.

He said slightly cooler conditions in NSW on Monday would be short-lived, with temperatures forecast to climb into the mid-30s again on Tuesday. In Sydney, the forecast maximum of 33C was about 11C above the October average.

“It will also be quite windy,” he said. “That means a number of places in NSW will have elevated fire risk.”

Hines said the “striking shift” in conditions moving through Victoria would reach southern parts of NSW on Wednesday, bringing heavy rainfall to some areas.

He said the low-pressure system was expected to peel away on Friday, taking the rain and winds with it, but cooler temperatures would continue into the weekend.