Two emergency warnings have been issued for bushfires burning north-west of Sydney and west of Wollongong.
More than 100 firefighters and six aircraft are responding to the Laws Farm fire, which is burning out of control at Lower Portland on the Hawkesbury River.
The blaze has already burned about 60 hectares of bushland north of Sackville.
Just after 7pm AEDT, the Rural Fire Service (RFS) said the immediate threat was easing and residents near Laws Farm Road were allowed to return.
The second blaze is threatening a small number of isolated rural properties in the area around the Old Hume Highway at Alpine.
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Firefighters are working to protect properties north of the railway and south of Ovington Road.
The RFS said crews were also back-burning along the railway line and as a result, there would be in an increase in fire and smoke while these this happens.
Ben Shepherd from the RFS said the Laws Farm fire had approached homes.
“There are dozens of properties around that Cumberland Reach area, some of them did have reasonably cleared areas around them, which allowed firefighters to work but we saw them working literally at the backs of homes, so it did escalate quite quickly,” he said.
“Obviously there’s a fair amount of work to do over the coming hours before we can get the fire under control.
“We have seen some spot fires as well on the eastern side of the river.”
The RFS added a southerly change was pushing smoke and embers to the north of the Lower Portland area and urged residents to be aware of the possibility of spot fires and ember attacks.
Watch-and-act remains for Taralga fire
Meanwhile, a watch-and-act alert remains in place for a blaze burning near Taralga, north of Goulburn.
The RFS says strong winds are fanning the Currawilla grass fire in the Upper Lachlan region.
“There are some rural properties that may come under threat… but once again we’re sending more fixed-wing bombers and also crews to that [fire],” Mr Shepherd said.
Two other fires in the Shoalhaven and Goulburn Mulwaree regions have been downgraded from watch-and-act alerts this afternoon.
The Wirritin fire and the Mountain Ash fire are now under control.
Total fire ban for many regions
A total fire ban is in place across most of the state today due to the hot, dry and windy conditions.
Earlier today RFS spokesman Brendan Doyle said low humidity and high temperatures had increased the fire danger across the state.
“Fires can start quite easily and spread quite quickly. Not only [are] firefighters going to be vigilant, but we’re asking people themselves to be vigilant,” he said.
“Report any new fires immediately because under these weather conditions, minutes can matter.”
Mr Doyle said firefighters did back-burn to strengthen containment lines.
Authorities warned of hazardous pollution levels across Sydney as a result of the back-burning operations.