Fire crews have returned to the Blue Mountains to fight a bushfire being fanned by gusty winds.

Authorities warn the blaze could continue to flare up throughout the afternoon due to forecast strengthening winds.

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While there is no immediate threat to homes, the fire alert has been upgraded to watch and act, after being downgraded to advice level late yesterday afternoon.

About 130 firefighters are on the ground, including Remote Area Firefighting Teams (RAFT), to focus on the fire that dropped off an escarpment.

The specialist RAFT personnel are trained to work in rugged, isolated areas.

Crews are concentrating their efforts between the cliff top and Little Switzerland Drive, including small areas of bushland burning in the Jamison Valley.

While there is no immediate threat to homes in the area, authorities have said residents should continue to monitor the situation and take advice from firefighters.

Firefighters are on standby near homes on the southern side of Wentworth Falls in case the fire burns towards properties.

The fire that burned out of control across 30 hectares in the Wentworth Falls area during the hours of Saturday morning was spurred on yesterday by heavy winds.

Bureau of Meteorology forecaster Dimitri Danchuk confirmed it would be “exactly the same situation today”, with winds reaching up to 80 kilometres per hour.

RFS spokeswoman Natalie Sanders said conditions were quiet over the fire ground throughout the night with 40 firefighters on standby and patrolling the area.

“Winds have remained low, so we haven’t seen those flare-ups like those on Friday night,” she said.

More water-bombing helicopters will be sent to the area throughout the day to assist teams on the ground.

Ms Sanders said while the immediate threat had passed, residents still needed to be vigilant.

“It’s near Horden Road and to the West of Table Land Road. So Residents in that area along with Coronation Road do need to be aware of what is happening on the fire ground today.

“There is no immediate threat to residents in that area but again we just advise that everybody stays up to date and makes sure they know what they are going to do if the fire does flare up again today.”

The New South Wales Rural Fire Service continue working to battle a bushfire in Wentworth Falls.