The ban will be in force across Wollongong, Shellharbour, Kiama, Shoalhaven, Wingecarribee and Wollondilly council areas due to a very high fire danger.

A total fire ban is also in place for Greater Sydney and other parts of NSW on Saturday.

"Hot, dry and windy conditions are forecast across parts of the state," the NSW Rural Fire Service said.

"Know your fire risk and what you will do if fire threatens."

A total fire ban helps limit the potential of fires developing and on these days outdoor fires are banned.

"You cannot light, maintain or use a fire in the open, or to carry out any activity in the open that causes, or is likely to cause, a fire," the NSW RFS said.

"General purpose hot works, such as welding, grinding or gas cutting or any activity that produces a spark or flame, are not to be done in the open."

The total fire ban commences at 12.01am on Saturday and finishes at 11.59pm the same day.

People are urged to be ready to act and report any unattended fire immediately by calling triple-0.