The statewide ban, which began at midnight, comes as temperatures across NSW are expected to range from the mid-30s to low-40s with the hot weather accompanied by high winds.

The Hunter Valley and surrounds will face extreme fire danger while the rest of NSW is set to experience severe to high fire danger.

The RFS warns that under extreme conditions homes that are specially designed and constructed to withstand a bushfire, prepared to the highest level and actively defended may provide safety.

Australian Associated Press