The RFS is now advising residents in Pleasure Point, Sandy Point, Alfords Point, Barden Ridge, Voyager Point, Illawong, Menai & Bangor to "remain vigilant throughout the day and keep themselves up to date by checking the NSW RFS website".
Mr Fitzsimmons said it was possible that winds could strengthen again and elevate the fire danger.
A blaze at Menai still continues to burn in a south easterly direction toward Barden Ridge - no homes are at risk but crews are on the ground focused on containing the fire.
Fire conditions eased later in the day, allowing firefighters to step up efforts to bring the blaze under control.
Despite the fire's size and its proximity to several suburbs, with some locals evacuated from their homes, no properties were known to be lost, the New South Wales Rural Fire Service said.
Authorities said wind speeds were not as severe on Monday, making it easier to battle the blaze. Residents in these areas should shelter in place.
A large bushfire that has threatened homes in Sydney is likely to have been deliberately lit, Australian authorities say.
"Most of those houses that burnt down were not from the fire front, it was from a spot fire or from a burning ember catching on fire on somebody's roof."
The grass fire began in Casula on Saturday afternoon and quickly spread through Moorebank, Wattle Grove, Holsworthy, Menai and Heathcote.
Over the weekend the blaze was declared an emergency a number of times but was downgraded to watch and act when winds dropped down to around 15 to 25 kilometres per hour.
Shane Fitzsimmons from the RFS said the fire was behaving "very aggressively".
He said the aircraft had unfortunately already been returned to the United States because they were always sent back by the end of March when temperatures were traditionally cooler.
"There is a lot of work still to be done today and maybe into tonight before we can call the fire contained".
"As we say all the time, no one tolerates this in the community".
NSW Police have launched an investigation into the cause of the fire and are appealing for witnesses, ABC reported.