Holiday-makers are being urged to postpone trips for 24 hours, with NSW bushfires forcing the closure of the Hume Highway and blocking routes between Sydney and the state's west.
Transport for NSW says a section of the Hume Highway connecting Sydney and Canberra has on Saturday been closed in both directions between the Old Hume Highway at Colo Vale and Narellan.
Picton Road is also closed at the M1 Motorway.
In the Blue Mountains, the Great Western Highway is closed in both directions between Hartley and Mount Victoria due to the emergency-level bushfire burning out of control in the Grose Valley.
The Bells Line of Road and Chifley Road are closed between Kurrajong and Lithgow as are Megalong Road, Jenolan Caves Road and Bowen Mountain Road.
Trains lines between Campbelltown and Moss Vale, to the south, and westwards between Katoomba and Bathurst have also been impacted.
The Princes Highway has been closed in both directions between Bewong and Conjola on the state's south coast.
NSW Police assistant commissioner Karen Webb said on Saturday the state's residents should delay all non-essential travel.
"The NSW Police message to motorists is today is not the day to start your holiday," she told reporters at NSW Rural Fire Service headquarters.
"Delay your travel until tomorrow.
Conditions will be much milder and you can have a better trip."
EMERGENCY WARNING - Gospers Mountain Fire (Hawkesbury and Lithgow LGAs)— NSW RFS (@NSWRFS) December 21, 2019
Fire continues to burn below the Bells Line of Road. The southerly change is due to impact this fire within coming hours. Video shows the fire approaching the Fruit Bowl along Bells Line Of Road, Bilpin. pic.twitter.com/0gvSEgsayL
Fire danger is rated "catastrophic" on Saturday in the Greater Sydney, Illawarra-Shoalhaven and Southern Ranges regions and "extreme" in the Hunter, the ACT and the Central Ranges.
Do you have a story tip? Email: email@example.com.