Australian residents lived in fear of a "megafire" Monday as dozens of bush blazes threaten to converge after already consuming thousands of hectares of land.

Officials also warned that a smoke cloud over Sydney may affect residents' health, as the broken promise of rain may make firefighters' already daunting task more difficult.

"The fuel bed is very, very dry. We've had a series of high wind, high temperature, low humidity days. That causes fires to run quite hard. For instance, the fire that started last Thursday ran 35 kilometers in one day," said Stuart Midgely, a New South Wales Rural Fire Service incident controller and the top coordinator for the Blue Mountains blaze.

As Wednesday promises more wind and higher temperatures, crews are working "to get containment lines in as deep as we can before that bad weather comes back and potentially blows the fires back up again," he said.

Compounding matters is "fairly widespread" lightning in western New South Wales, storms that are being accompanied by little to no rain, said Rural Fire Service Commissioner Shane Fitzsimmons.

"We are not expecting any meaningful rainfall to be of any benefit across any of the current fire grounds," he said, noting that the rain forecast for the weekend never materialized.

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Destruction spreading

The fires are swallowing up large areas of bush in New South Wales, Australia's most populous state, where authorities have declared a state of emergency. More than 200 homes have been damaged or destroyed.

One in three Australians live in New South Wales.

In at least one town, Bilpin, firefighters were forced to stop containing the fire to focus instead on protecting homes.

Forecasts of high temperatures, low humidity and strong winds over the next few days in the Blue Mountains region, west of Sydney, have state officials especially concerned.

Sixty-two fires are raging in the state, 14 of them out of control, authorities said Monday. More than 1,000 firefighters are battling the blazes that have burned 116,167 hectares (about 287,000 acres) -- an area roughly the size of Los Angeles.

Local officials fear that three large fires spreading through the Blue Mountains could merge to form one huge inferno.

"If they do join up and push to the south, there is the potential that many heavily inhabited suburbs along the Great Western Highway in our Blue Mountains region may be directly impacted by fire," said Alex Chesser, a spokesman for the fire service.

"It is unusual to see fires this size so close to Sydney," he said. "And this one does pose a significant amount of risk to hundreds of thousands of properties in the Blue Mountains area, should the wind change."

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Total fire ban

The state of emergency issued by authorities gives firefighters and police the authority to carry out measures such as cutting off water, power and gas and ordering mandatory evacuations of areas at risk.

Firefighters in the Blue Mountains worked hard Monday "back-burning" -- using small, controlled fires to burn away flammable material in a bush fire's expected path -- to try to get the upper hand on the most threatening fires.

A total fire ban is in place for the Greater Sydney region until further notice, officials have said, meaning no fire may be lit in the open, and all fire permits are suspended.

The fires have spread a cloak of smog over Sydney in recent days.

The bush fires in the area spread out of control Thursday amid high temperatures and powerful winds. Emergency officials said the region is emerging from a very dry winter and has had little rain in recent months.