CANBERRA, Australia — New South Wales (NSW), Australia’s most populous state, is battling “catastrophic” conditions Tuesday as wildfires spread, with Sydney surpassing 42 degrees Celsius (108 degrees Fahrenheit).

Hundreds of emergency personnel have been fighting more than 130 blazes that have burnt through bushland, some of which have threatened homes, according to the NSW Rural Fire Service.

Bush fires are still burning in Tasmania, Victoria, and South Australia states amid the most wide-ranging heatwave in a decade.

“The word ‘catastrophic’ is being used for good reason,” Prime Minister Julia Gillard told Channel Seven television in an interview Tuesday, after thousands of people were forced from their homes in the nation’s south. “This is a very dangerous day.”

Tennis players at the Sydney International, a lead-up tournament for next week’s Australian Open in Melbourne, played through temperatures as high as 41.4 degrees at Olympic Park. They draped themselves in ice towels at changeovers during matches and some took ice baths to help them recover.

Emergency warnings were posted in at least seven areas in NSW, including near the regional centers of Wagga Wagga, Bega, and Cooma, while the Hume Highway — the main link between Sydney and Melbourne — was cut by fire near the town of Tarcutta.

A “catastrophic” alert, meaning any fire that starts has the potential to cause significant loss of life, has been issued for the NSW districts of Illawarra and Shoalhaven and the Southern Ranges south of Sydney, Deryn Griffiths, a forecaster with the Bureau of Meteorology, said in a phone interview.

Extreme Heat

The temperature at Sydney’s Observatory Hill reached 42.3 degrees Celsius at 2:03 p.m. Tuesday, the highest temperature since Jan. 1, 2006, according to the bureau. A cooler change is expected to bring relief tonight, it said.

Australia’s hot, dry climate makes bush fires a major risk in the southern hemisphere’s summer. The worst fires in the nation’s history — the so-called Black Saturday blazes — killed 173 people as they swept through rural Victoria in February 2009.

Eighty percent of the country recorded temperatures above 40 degrees Celsius last week, with such conditions forecast to continue in parts of South Australia, Victoria, and New South Wales, according to the weather bureau.

Fire Bans

Gillard yesterday surveyed the devastation in the island state of Tasmania after blazes destroyed about 100 properties and displaced about 3,000 people.

Three major fires in Tasmania’s southeast, center and northwest are still burning out of control, Deputy Premier Bryan Green told ABC radio. While conditions in the state are cooling, stronger winds may hamper authorities in bringing the fires under control and move to a recovery phase, he said.

“My thoughts are with New South Wales as they go through this day,” Green said. “Here in Tasmania it was frightening as the situation unfolded, so people must heed the warnings.”

An emergency warning was installed for the area between Forcett and the Tasman Peninsula in Tasmania, as the fire that destroyed much of the town of Dunalley last week flared up again.

Police in Tasmania have organized convoys involving 395 vehicles and about 750 people to escape from the Tasman Peninsula. About 500 vehicles and 1,500 people remain at the town of Nubeena on the peninsula, Tasmania Police said in a statement.

Total fire bans are in place today for much of Victoria state, where more than 7,000 hectares (17,300 acres) has been burned by a fire northwest of Portland, according to authorities. A blaze has also affected Sunbury, near Melbourne.

Strong Winds

Hot temperatures in southeast Australia Tuesday will be exacerbated by strong winds, which could quickly spread fires, forecasters said.

“Southeast Australia has been under extreme heat conditions for many days,” NSW Fire Service Commissioner Shane Fitzsimmons told Australian Broadcasting Corp. television. “That’s had a profound effect on depleting the moisture across the landscape which results in the grassland and forested areas being very susceptible to ignition.”

Along with the threat of fire, heatwaves pose a general risk to health, said Margaret Loughnan, a researcher at Melbourne’s Monash University.

Health Risk

“Heatwaves in Australia harm more people than any other natural disaster,” Loughnan said in an emailed statement. “Extreme heat events pose a risk to the health of all individuals, especially the elderly, young children and the chronically ill.”

Siva Kumar, 32, intended to quickly return to his air-conditioned office while on his lunch break in Sydney’s central business district.

“It is as oppressive as it can get,” the software support engineer said. “This just shows the difference between hot and hottest.”