Sydney  - More than 1,000 volunteer firefighters backed by 70 aircraft were tackling more than 100 forest blazes in Australia's parched south-east Sunday.

Temperatures topped 40 degrees in Sydney and across New South Wales as emergency services warned that conditions were too extreme to attempt to turn back fires bearing down on homes.

Most of the fires are in remote forests and were started Friday by lightning strikes, officials said.

Rural Fire Services spokesman Anthony Clarke said some residents had waited too long to evacuate.

"We encourage people to now stay with their properties and work with firefighters to defend those homes," he said.

A decade of drought has left tinderbox conditions in many parts of the state, prompting a total ban on open fires. The Blue Mountains National Park, a popular day-trip for tourists visiting Sydney, remained closed because of the fire danger.

Weather Bureau forecaster Michael Logan said lower temperatures were on their way but firefighters needed to hold the line until it came.

"And it's hot, gusty north-westerly winds, up in the severe to extreme categories," Logan said. "There's a cool change expected overnight which will see temperatures drop dramatically."

In and around Melbourne, which in February saw forest fires north of the city claim 173 lives, the emergency passed when the state of Victoria received drenching rains and temperatures plummeted.  (dpa)