Firefighters have had their first chance to conduct a "direct attack on fires" as a result of damp conditions in parts of the state on Christmas Day.

About 2000 firefighters and 400 fire trucks were in the the field on Wednesday as more than 70 fires continued to burn across the state, despite cooler temperatures and some rainfall.

NSW RFS Crews conducting a backburn on the Gospers Mountain Fire at Colo last week. Credit:Wolter Peeters

"A key change from yesterday is that we have been able to do some offensive firefighting, we've been conducting direct attacks onto fires in the Blue Mountains," a spokesman for the NSW Rural Fire Service said.

He said the direct firefighting efforts have involved fighting smaller blazes to "slow the spread of fire before it emerges as an identified containment line".