flickr.com/jemsweb

NSW firefighters are battling uncontained bushfires north and south of Sydney as the weather bureau predicts hot, dry and windy conditions creating a very high to extreme fire danger.

A total fire ban has been imposed for most of southern NSW as Rural Fire Service (RFS) firefighters respond to a total of seven bushfires across the state.

The RFS says it is particularly concerned for dry bushland with the Bureau of Meteorology (BOM) predicting hot, dry and windy conditions creating a "very high to extreme fire danger".

Temperatures are expected to soar past 40 degrees celsius in parts of the state, including in Sydney's west.

"All parts of the state except the far north coast are in for very high temperatures," RFS Assistant Commissioner Rob Rogers said on Tuesday.

"The high temperatures, low humidity and winds of varying strengths make for extreme fire danger in areas where there is no ground moisture."

Firefighters are battling two uncontained fires, one near Singleton in the Hunter Valley and the other south of Sydney, in the Wingecarribee region.

"The fire at Morton National Park, Wingecarribee, is not controlled and we have had trouble accessing it because it is in very rough terrain," Mr Rogers said.

"We have aircraft working on that fire and the Singleton fire."

Crews have also been working on a 200-hectare blaze which has been burning for a day south of Goulburn.

"We're working in conditions - westerly winds up to 45km/h - which make firefighting extremely difficult," he said.

"But we have aircraft working on the fire and made some good containment overnight."

Mr Rogers said fire crews had 10 aircraft available for use.

"On a day like today, if a fire starts we will throw aviation resources at it as soon as we can," he said.

"That won't necessarily put it out straight away but can significantly restrict its spread."

With the bushfire season now well underway, Mr Rogers said, landholders should have a fire plan for their properties and be aware if they are in a position to stay and defend their property or if they need to leave.

The other bushfire activities to which RFS are responding to are at Wollondilly, south of Sydney, Corowa, in the state's south, Bland in central NSW and Coffs Harbour, on the north coast.