Winds that have fanned about 100 blazes across the state started to change direction late yesterday afternoon, putting new communities at risk as fires are pushed in new directions.

Of the 100 fires, about 40 were uncontained at 5.30pm.

Between 20 and 30 homes have been destroyed in Springwood, in the Blue Mountains and many more are under threat.

There are also unconfirmed reports of properties being lost at North Doyalson, on the Central Coast; at Lithgow; at Yanderra and Balmoral, in the Southern Highlands; and in Port Stephens, where a fire is burning near Newcastle Airport which has been closed.

“If we get through today losing less than 100 homes, we’ll have been very lucky,” Rural Fire Service spokesman Anthony Clark said.

RFS Deputy Commissioner Rob Rogers said it had been a nightmare day.

“It’s probably the most serious fire risk we’ve faced since the early 2000s,” he told ABC Radio.

With multiple fires in the Blue Mountains area, police asked the public to postpone non-essential travel in order to keep the roads clear for firefighters.

Residents in the Springwood, Yellow Rock, Winmalee, Emu Heights, Mt Riverview and Castlereagh were told to take shelter and protect themselves from the radiant heat.

Some firefighters have suffered injuries, including one who’s been taken to hospital with burns.

A southwesterly change moved through Mittagong around 4pm (AEDT), bringing wind gusts of up to 90 km/h.

It would move through Sydney during the early evening.

“It’s coming through from the southwest,” Mr Clark told reporters.

“So communities to the north of some of these fires are now being affected.”

An emergency warning has been issued for a fire at Ruttleys Road at North Doyalson, on the Central Coast.

“There are unconfirmed reports of (one or two) properties being destroyed there,” the RFS spokesman said.

In the Southern Highlands, communities around Bargo were warned to expect large fires, ember attacks and smoke from about 5pm as the change moved through.

Residents advised to evacuate to Bargo earlier in the day were being told to avoid the area.

Elsewhere in NSW, fires of grave concern to authorities are burning at Leppington, near Camden, west of Sydney, at South Nowra, on the south coast, and at Muswellbrook, in the Hunter Valley.