Fire fighters are continuing to battle an out of control blaze in the NSW Blue Mountains.

About 220 firefighters and five helicopters fought to contain the major fire in the Blaxland-Warrimoo area overnight.

Stronger than expected southerly winds hampered efforts on Friday, but the conditions eased and fire fighters began back burning behind homes in the area shortly after 11pm, a spokeswoman for the Rural Fire Service said.

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The RFS have downgraded the fire to “watch and act”, but the spokeswoman said the danger is not over yet.

“We’re asking people to be aware, particularly of embers,” the spokeswoman said.

On Friday afternoon the fire service upgraded the out-of-control blaze to the highest level of bushfire alert.

The fire crept dangerously close to properties in the area, while the Great Western Highway was temporarily closed and the train service was paused between Glenbrook and Springwood.

There are 55 fires burning throughout the state and six are uncontained.

The RFS has total fire bans in the Greater Hunter region, the Central Ranges, the Northern Ranges, the Upper and Central West Plains and the Northern Slopes.

Temperatures are expected to be cooler in the Blue Mountains on Saturday with a top of 27 and a chance of afternoon showers.