WSJournal. Winter here. Australia Has A Heat Wave.

WSJournal. Winter here. Australia Has A Heat Wave.

SYDNEY—Australian authorities downgraded the wildfire threat posed by extreme heat conditions across the country Wednesday as cooling temperatures allowed emergency services to bring a string of blazes under control.

Emergency alerts remain for five locations across New South Wales, Australia's most populous state, though downgraded from the "catastrophic" warnings that were in place on Tuesday. Fires continued to burn in Victoria, Tasmania and in the Australian Capital Territory, where the federal government is based. State capitals have so far been largely spared, with most of the burning affecting farmland and bush.

Officials say a heat wave that has swept the country, described as a "dome of heat," is moving north toward the coal rich state of Queensland, where temperatures are expected to reach 104 degrees Fahrenheit, (40 degrees Celsius), in Brisbane, the state capital.

Residents fled the worst-affected areas on Tuesday, and homes and properties have been damaged and destroyed.

Authorities haven't reported any fatalities, but in Tasmania, an island state off the country's south, forensic crews are continuing to search the area as they seek to account for a number of missing people. More than 100 properties have been destroyed. Police expect the numbers of missing people to dwindle as residents return to their properties.

Wildfires are raging through parts of southern Australia, leaving behind a path of destruction. The WSJ's Enda Curran explains how current weather conditions have left the country ripe for wildfires.

Temperatures hit about 112 degrees in some parts of New South Wales state on Tuesday and reached 108 degrees in the state capital Sydney., with the flames also fanned by strong winds.

The extreme heat has led the Bureau of Meteorology to add the colors deep purple and pink to its interactive weather chart after it extended the chart's range to capture forecasts up to about 130 degrees. Previously the colors black and orange signified the highest temperatures.

At one point more than 130 fires were blazing across New South Wales, threatening homes and property. The federal government in Canberra has activated a disaster-response plan to coordinate firefighting efforts with military assistance.

In Sydney, the country's largest city and financial hub, firefighters extinguished a blaze in an electrical substation in the country's nuclear research body, the Australian Nuclear Science and Technology Organization. An on-site nuclear reactor was shut down as a result. A representative said the event wasn't linked to the hot weather.

Located on the east coast of Australia, New South Wales boasts dozens of national parks and reserves. In Bega, along the southern coast, temperatures early Tuesday shot up within an hour, rising to 100 degrees by 9 a.m. local time.

Hallie Fernandez-Markov, 54 years old, owns a guesthouse and farm in Warrigal Range, located in southern New South Wales, in the heart of one of the danger zones. She fled her home with her partner and 6-year-old child as a fire came within a little over a mile of her property. Three of her guests also left.

"When we decided to evacuate, we just grabbed the photo albums, the computers, the jewelry, our dogs and child and left," Ms. Fernandez-Markov said when reached by telephone. Her family moved to a friend's house farther north.

"There is a lot of smoke and it is oppressively hot outside," said Ms. Fernandez-Markov, a native of upstate New York.

Residents in the hardest-hit areas were advised to seek shelter and Prime Minister Julia Gillard urged them to stay vigilant and follow the advice of emergency service providers.

Temperatures hit about 112 degrees in some parts of New South Wales state on Tuesday and reached 108 degrees in the state capital Sydney., with the flames also fanned by strong winds.

The extreme heat has led the Bureau of Meteorology to add the colors deep purple and pink to its interactive weather chart after it extended the chart's range to capture forecasts up to about 130 degrees. Previously the colors black and orange signified the highest temperatures.

At one point more than 130 fires were blazing across New South Wales, threatening homes and property. The federal government in Canberra has activated a disaster-response plan to coordinate firefighting efforts with military assistance.

In Sydney, the country's largest city and financial hub, firefighters extinguished a blaze in an electrical substation in the country's nuclear research body, the Australian Nuclear Science and Technology Organization. An on-site nuclear reactor was shut down as a result. A representative said the event wasn't linked to the hot weather.

Located on the east coast of Australia, New South Wales boasts dozens of national parks and reserves. In Bega, along the southern coast, temperatures early Tuesday shot up within an hour, rising to 100 degrees by 9 a.m. local time.

Hallie Fernandez-Markov, 54 years old, owns a guesthouse and farm in Warrigal Range, located in southern New South Wales, in the heart of one of the danger zones. She fled her home with her partner and 6-year-old child as a fire came within a little over a mile of her property. Three of her guests also left.

"When we decided to evacuate, we just grabbed the photo albums, the computers, the jewelry, our dogs and child and left," Ms. Fernandez-Markov said when reached by telephone. Her family moved to a friend's house farther north.

"There is a lot of smoke and it is oppressively hot outside," said Ms. Fernandez-Markov, a native of upstate New York.

Residents in the hardest-hit areas were advised to seek shelter and Prime Minister Julia Gillard urged them to stay vigilant and follow the advice of emergency service providers.

Smoke from a bush fire was visible from Park Beach, Tasmania, on Friday.

The Australia-wide heat wave extends a four-month run of scorching temperatures, according to the Bureau of Meteorology, with a record six consecutive days over 102 degrees. The previous record was four straight days, set in 1973.

"This event is continuing with further significant records likely to be set," the bureau said.

A helicopter joins the fight on the grass fire near Wagga Wagga, in the interior of New South Wales.

Jan Davis, chief executive of the Tasmanian Farmers and Graziers Association, said the wildfires have destroyed an area that accounts for 10% of Tasmania's agricultural earnings by burning thousands of hectares of crops and killing animals. Insurers have received claims valued at more than 42 million Australian dollars (US$44 million) from people in Tasmania, the Insurance Council of Australia estimated in a statement Tuesday. The figure is more than 60% higher than an initial estimate and is expected to grow. The ICA's chief executive, Rob Whelan, said it could be some time before a full assessment of the damage is completed.

Analysts have yet to gauge the impact of the fires on the wider economy, though some said the disruption to tourism during the current peak season would likely have the biggest impact.

Australia has been hit by a spate of extreme weather in recent years. In 2009, 173 people were killed by wildfires in Victoria, while Queensland state was hit by flooding and cyclones in 2011. Last year, a decadelong drought that ravaged the country's farms was declared over after a period of heavy rains.

Write to Enda Curran at enda.curran@wsj.com

Corrections & Amplifications
Hallie Fernandez-Markov fled her home with her partner and 6-year-old child. An earlier version of this article misidentified her partner as her husband.