The latest on the NSW bushfires

NSW is preparing to endure another day of catastrophic fire danger in a season that has now seen eight lives and hundreds of homes lost.

The latest information:

WHERE ARE THE FIRES?

There were 100 fires burning across the state on Friday, with half uncontained.

The Rural Fire Service said their main concerns are the Gospers Mountain megafire northwest of Sydney and the Green Wattle Creek blaze southwest of Sydney.

They are also tackling fires in the state's south in the Shoalhaven area, between Batemans Bay, Ulladulla, and Sussex Inlet Road area.

WHAT'S THE DAMAGE?

The death toll rose from six to eight when two volunteer firefighters were killed after a tree fell into the path of their tanker near Buxton.

Geoffrey Keaton, 32, and 36-year-old Andrew O'Dwyer, who had been helping to battle the Green Wattle Creek blaze, died on Thursday night.

The pair, both fathers, have been hailed as heroes.

Almost 800 properties have been lost so far this season and the RFS has warned that number is almost certain to rise on Saturday.

About three million hectares of land has been burned so far this season.

WHAT WARNINGS HAVE BEEN ISSUED?

A seven-day state of emergency was declared on Thursday.

Saturday will see catastrophic fire danger in Greater Sydney, Illawarra/Shoalhaven and the Southern Ranges. There is extreme fire danger in the Greater Hunter and Central Ranges.

A statewide total fire ban remains in place.

WHAT IS THE FORECAST?

The mercury is expected to reach the mid-40s on Saturday and strong winds are forecast.

The RFS and NSW Police have strongly urged people to delay their travel until Sunday or after, with fears motorists could get trapped on roads if fires spread.

Part of the Princes Highway on the South Coast will be closed near Ulladulla, and the RFS said there's a "fair chance" the Hume Highway will also be affected.

Back burning in the Blue Mountains closed the Great Western Highway in both directions between Blackheath and Little Hartley on Friday evening.