NSW bushfire conditions to worsen, with 100 blazes still burning

Firefighters are battling more than 100 blazes across NSW, with conditions expected to worsen again early next week as temperatures rise.

Smoke from bush and grass fires burning around Sydney will see the city endure another hazy day on Sunday, the Rural Fire Service says.

One hundred and eleven fires were burning across the state on Saturday night, 60 of which were not contained.

Some 1500 firefighters were tackling the blazes and there was no let-up on the horizon, Greg Allan from the RFS said.

"Tomorrow we're seeing a lot more widespread very high fire danger," he told AAP.

"We will see conditions deteriorate with worsening weather early into mid-next week. We're going to be seeing a lot more higher temperatures across the state."

Total fire bans have been issued for the Central Ranges, Northern Slopes and North Western areas amid very high fire danger ratings on Sunday and more bushfire smoke will affect the Sydney Basin, the fire service said.

"Smoke from fires burning on the outskirts of Sydney will settle across the Sydney Basin again overnight and tomorrow," the RFS tweeted.

"There is a possibility the smoke will clear slightly but remaining dense throughout the day."

An emergency warning issued on Saturday afternoon for the Gospers Mountain fire in Wollemi National Park northwest of Sydney was later downgraded to advice level.

The Ruined Castle fire in the Blue Mountains remained at watch and act level on Saturday night.

Maximum temperatures next week are forecast to reach the high 30s or early 40s in areas including Dubbo, Orange, Mudgee, Moree, Bourke, Parkes and on Sydney's western fringe at Penrith.

Authorities have warned people to remain vigilant about their health as air quality remains poor in parts of Sydney.

Some 724 homes, 49 facilities and 1582 outbuildings had been destroyed so far this fire season. Six people have died and 2.7 million hectares have been scorched.