Extreme weather conditions in NSW

SYDNEY - Extreme weather conditions hit NSW yesterday with temperatures exceeding 40C closely followed by strong southerly winds.

Hundreds of firefighters worked to contain about 20 bushfires burning across the state as temperatures reached a maximum of 44.7C in Singleton, in the Hunter Valley.

The high temperatures also caused a power blackout in areas on the south coast for two hours.

NSW transmission company, TransGrid, was forced to shed some customer load after a high level of electricity consumption caused two large generating units to fail, a company spokesman said.

Temperatures in Sydney surpassed the predicted 35C in the city, with Observatory Hill recording a maximum of 40C - 5.3C hotter than on Tuesday.

Singleton hit the scorching heights yesterday, reaching a peak of 44.7C while the hottest temperature in the Sydney area was reached at Sydney Airport where the mercury rose to 41.8C. Record temperatures were broken on the mid-north coast at Kempsey, where temperatures of 41.8C broke the record from December 23, 1972, of 40.6C.

But the hot weather would not last as a southerly wind blew through the state. "A southerly blast has come through most of Sydney now," a senior forecaster at the Bureau of Meteorology said.

"There is a much cooler change coming through ... "

The strong winds passing through Sydney were causing havoc as trees and branches were blown on to houses and into roads.

The State Emergency Service (SES) was responding to about 30 jobs across the city but expected more calls as the winds spread throughout the state, an SES spokesman said.

There were also fears the change in weather conditions could cause bushfires to escape containment lines. "All fires are contained but all this could change as the southerlies come through," a NSW Rural Fire Service spokesman said.

AAP