The Greater Sydney, Illawarra/Shoalhaven, New England, northern slopes and north western regions are all due to face extreme fire danger on Tuesday.
Under extreme fire danger, people should prepare to protect their life and property, check their bushfire plan and ensure their property is fire ready.
Travel through bushfire risk areas should also be reconsidered.
The regions are among seven facing total fire bans in NSW on Tuesday amid the forecast of deteriorating conditions.
Warm and dry weather with fresh northwesterly winds is forecast, with potentially severe afternoon and early evening thunderstorms forming along the northern half of the coast and ranges.
A milder, fresh south to southwesterly change is expected to spread across the state throughout the day.
Firefighters late on Monday gained the upper hand on an out-of-control blaze in inaccessible terrain northeast of Tenterfield.
The 65ha bush fire was one of several in the northern Tablelands expected to spread east under westerly winds on Tuesday.
The Glen Innes RSL and Tenterfield Showground has been opened to accommodate locals leaving early ahead of forecast extreme fire danger.
As of Monday evening, about 80 bush and grass fires were burning across the state, including a handful out of control.
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