More than 15 emergency-level fires, including a blaze in South Turramurra in Sydney's north shore, ravaged NSW on Tuesday, as 3000 firefighters battled flames against dangerous and unpredictable winds late into the evening.

Warnings of "catastrophic conditions" issued on Monday allowed many people to evacuate ahead of the outbreaks, but residents who had stayed put were forced to flee the approaching flames or were left debating whether to stay or leave their homes into the early hours of Wednesday morning.