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, north of Sackville.
The Rural Fire Service (RFS) has told residents on five roads in the area that it is too late to leave.
The second blaze is threatening a small number of isolated rural properties in the area around Old Hume Highway and Ovington Road at Alpine.
Ben Shepherd from the RFS says the Laws Farm fire has already approached homes and crews are working to protect properties.
Meanwhile, a watch-and-act alert remains in place for a blaze burning near Taralga, north of Goulburn.
Total fire ban for many regions
A total fire ban is in place across most of the state on Sunday due to the hot, dry and windy conditions.
Earlier on Sunday RFS spokesman Brendan Doyle said low humidity and high temperatures had increased the fire danger across the state.
He 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.