Most of NSW's east coast will be under severe or very high fire danger on Tuesday as the state heads into the first of two "tough days" for the week.
Six lives and 530 homes have been lost since the state's bushfire season hit some weeks ago, with more than 420 homes destroyed in the past fortnight alone.
On Monday night there were 51 grass and bush fires burning around NSW, all at "advice" level, with 28 yet to be contained, the RFS posted on Twitter.
"More than 1300 firefighters continue work on these fires tonight, ahead of forecast hot, dry and windy conditions tomorrow," the agency said.
Tuesday and Thursday will be "tough days", RFS Deputy Commissioner Rob Rogers told reporters in Sydney on Monday.
Parts of the state will be under severe fire danger on Tuesday including Greater Sydney, Greater Hunter, Illawarra/Shoalhaven, Southern Ranges and Central Ranges fire regions.
These regions, along with the Northern Slopes and North Western regions, will also be under a total fire ban.
Much of the rest of eastern NSW and the ACT will be under very high fire danger.
Some 1.6 million hectares of land have been lost - more land loss than the entire 1993/1994 season, Mr Rogers said.
Firefighters are battling a firefront of some 6000 kilometres, the equivalent distance of a return Sydney-Perth trip, he said.
Mr Rogers said firefighters were "singularly focused" on preventing further loss of life and property and warned people to stay alert.
"Even though it's not a catastrophic danger (this week) it's still going to be bad fire days," he said.
He urged anyone who had not yet been affected by bushfires to "please use this as a wake-up call", warning them to take steps including cleaning out gutters and having a fire safety plan in place.
Premier Gladys Berejiklian said the past week was a reminder "the summer isn't going to be pleasant in terms of the bushfire risk".
"I ask everyone to maintain their vigilance," she said.
Emergency Services Minister David Elliott said the biggest risk in the coming days would be firefighters becoming fatigued.
The minister revealed a DC10 air tanker had been drafted in from North America and would help drop up to 38,000 litres of water and retardant on blazes.
It brings the number of air tankers operating this season to five, up from three.
He also said efforts would be bolstered by help from New Zealand firefighters.
Australian Associated Press