THE Rural Fire Service in New South Wales says hot winds, low humidity and soaring temperatures are making three large bushfires burning in the state difficult to control.

The RFS says helicopters and firefighters are working to control two bushfires both covering 100 hectares in the Wingecarribee region south of Sydney, and near Singleton in the Hunter Valley.

Meanwhile,aircraft and 40 firefighters have contained a blaze south of Goulburn .. which had been burning since yesterday, but it's expected to flare up again this afternoon amid hot winds.

Four other fires at Wollondilly, Corowa, Bland and Coffs Harbour are now under control.

AAP