Residents in Sydney's south-west are breathing a sigh of relief after a severe bushfire that has burnt more than 2,400 hectares eased overnight.
The fire resulted in hundreds of people being evacuated from their homes on Saturday evening with flames nearly reaching properties at Holsworthy and Wattle Grove and spot fires later threatening Sutherland and Menai.
Firefighters fight flames close to homes in Corryton Court, Wattle Grove in Sydney, Saturday, April 14, 2018.
The NSW Rural Fire Service says it can't yet confirm the level of damage and the number of properties affected, but the fire had burned 2,430 hectares around the Holsworthy and Menai areas and damaged an army base.
Firefighters battle the blaze near Holsworthy on Saturday afternoon.
"Temperatures could be a little higher [today] but we'll also have increased humidity, so that plus the slower speed of the winds will certainly assist firefighters bringing this fire under control".
"We have had reports of impact on properties in west Menai and Barden Ridge but our crews at the moment are exclusively focused on fighting the fire", he told AAP in the evening.
Residents in Sandy Point and Alfords Point were told on Sunday morning to continue monitoring conditions while those in Illawong, Bangor and Picnic Point were warned of ember attacks and potential new spot fires.
Police are investigating whether the fire was deliberately lit. (9NEWS) More than 500 firefighters have worked to contain the blaze over the weekend.
The temperature may remain a cause for concern, according to the RFS Deputy Commissioner Rob Rogers.
Some remembered bad bushfires in the 1990s when homes were destroyed, and were determined to stay and extinguish embers or spot fires as they broke out.
Police believe the fire may have been lit on objective and are appealing for witnesses to contact them.
"Still quite a hard day ahead (on Monday)", he told the Nine Network.
Heathcote Road remains closed between Macarthur Drive and New Illawarra Road while Old Illawarra Road at Barden Ridge has reopened.