The Bureau of Meteorology has formally declared a looming El Niño for Australia, the first in eight years.

Tuesday afternoon’s announcement from the weather bureau came two months after the World Meteorological Organisation announced an El Niño was underway.

The major climate driver in the Pacific Ocean is the opposite of La Niña, and is linked to hot, dry weather, which can increase the risk of bushfires in Australia. It will also increase the likelihood of further record high global temperatures.

Dr Karl Braganza, from the bureau, said Australian was likely in for a hot summer. BOM would be “closely monitoring” how dry things get, in case fire and drought risks rose.

The declaration came as further total fire bans were declared in greater Sydney, the greater Hunter and upper central-west plans for Wednesday. Extreme fire danger is forecast for greater Sydney and the Hunter. For more details, see the NSW Rural Fire Service website.

On Tuesday, fire warnings for parts of NSW were upgraded to catastrophic, amid a heatwave across south-eastern Australia, spurring the closure of dozens of schools.

A total fire ban was earlier declared for the NSW south coast and greater Sydney region, as temperatures soared to September records.

Sydney reached 34.6 degrees on Tuesday afternoon – its equal highest September temperature on record, according to forecaster Weatherzone. At Sydney Airport, it was 35.7 by 2pm, topping its previous September record of 35.6 degrees from 2000.

But early afternoon, the fire risk had escalated to catastrophic for parts of the south coast, due to stronger than forecast winds.

The urgent change in advice level came after dozens of schools in NSW were closed on Tuesday when extreme fire danger ratings were declared.

More than 3000 children were told to stay home on Tuesday when the NSW Department of Education decided, in consultation with the NSW Rural Fire Services, to temporarily shut 20 schools.

The ABC reported that at least nine other schools had told families that they would also not run on Tuesday.

The fire ban and school closures apply across areas including the Bega Valley and Eurobodalla Shire.

It followed the declaration of a total fire ban for the south coast and greater Sydney region on Tuesday, with temperatures forecast to reach 33 degrees.

Angus Hines from the Bureau of Meteorology said Wednesday would be hotter, with 34 degrees, and parts of South Australia and Queensland would also feel the heat.

“Most of Australia is sitting at moderate or high fire [danger] for the next few days,” he said.

“The south coast of NSW has a small area of extreme fire danger there, overlapping with the heatwave conditions on Tuesday.”

RFS far south coast coordinator Chris Anderson told the ABC Tuesday would be extremely challenging.

“Extreme conditions mean you need to take action now to protect your life and property,” he said.

“Under an extreme fire danger rating fires will spread quickly and become extremely dangerous.

Tuesday marked was the first total fire ban for greater Sydney since late November 2020, NSW Rural Fire Service spokesman Ben Shepherd said.

“Looks like a couple of hot, dry and windy days on the way,” he said.

People should be prepared, RFS Commissioner Rob Rogers said.

“It’s the worst risk we’ve faced since the Black Summer fires of 2019,” he said.

Tweet from @NSWRFS

Conditions in Queensland are expected to ease on Tuesday and Wednesday with only smoke alerts issued, Fire and Emergency Service deputy commissioner Joanne Greenfield said.

By Thursday the high to extreme fire dangers will be more widespread, including a large part of the Channel Country in Queensland.

South-east Queensland can expect a cooler change to roll through on Friday, according to the BOM.

Meanwhile, there was a severe wind warning in place for Tuesday in parts of the NSW Snowy Mountains and south-west slopes. Winds were expected to become more damaging and widespread across the state on Wednesday, ahead of a cold front.

By 1pm Tuesday, the NSW RFS had issued a warning for a fire at Bombala, in the Bondi Nature Reserve, in the Snowy-Monaro region.

“The fire is burning in an easterly direction towards the Monaro Highway. There is currently no homes under threat, but smoke will be visible in the area,” it said.

Dozens of other fires were also burning across the state. See all details here.

Tasmanian authorities also issued an emergency warning for a fire at Friendly Beaches about 4pm on Tuesday, as well as several other alerts.

Tweet from @QldFES

Mr Hines said the winds had emergency services on alert.

“On Wednesday we’re going to see some warm windy weather around Sydney and the Hunter, with extreme fire danger forecast in those regions.”

Fire crews have been busy in the NSW Hunter and south-eastern parts of Queensland, with a fire burning at Beerwah on the Sunshine Coast shifting between advice and watch-and-act for days.

-with AAP