Greater Sydney, Hunter and Illawarra/Shoalhaven residents are bracing for "off the scale" fire danger on Tuesday.
WHAT DOES THE RATING MEAN?
* The fire danger for Tuesday has been rated "catastrophic".
* "It's where people die", says NSW RFS Commissioner Shane Fitzsimmons.
* Residents are being warned fires under these conditions are hard to suppress and homes will burn.
* People are being told to leave for their survival now.
* This is the first catastrophic declaration for Sydney since a new rating system came into effect 10 years ago.
WHICH AREAS ARE AFFECTED?
* Greater Sydney: 35 local government areas running from beachside suburbs like Manly to the Blue Mountains in the west. The danger areas are listed below.
* Sydney West and Inner West: Burwood, Canada Bay, Strathfield, Blacktown, Campbelltown, Canterbury-Bankstown, Cumberland, Fairfield, Liverpool, Parramatta Penrith, Sydney (includes some inner west suburbs).
* Sydney East: Randwick, Sydney, Waverley, Woollahra.
* North and North West: Camden, Central Coast, The Hills, Hawkesbury, Hunters Hill, Ku-ring-gai, Lane Cove, Mosman, North Sydney, Northern Beaches, Ryde, Willoughby.
* South and South West: Georges River, Kogarah, Sutherland.
* The Hunter: Cessnock, Dungog, Lake Macquarie, Singleton and the Upper Hunter.
* The Illawarra and Shoalhaven areas south of Sydney.
HOW DANGEROUS WILL IT BE?
* Australia's worst bushfire tragedy was the Black Saturday fires of February 2009, which killed 173 people and destroyed thousands of homes. It would have carried a catastrophic rating under the present system.
* The current fire danger flags a similar level of destructive force.
* The catastrophic rating for Greater Sydney is "unprecedented" but there have been one or two warnings for other parts of the state in the past decade.
* "We got to keep reminding ourselves that catastrophic is off the conventional scale," Mr Fitzsimmons says.