The 109,000 hectare blaze, known as the Green Wattle Creek fire, is burning just 3.5 kilometres from the jail, NSW Rural Fire Service (RFS) data shows.

The RFS says conditions around the fire ground are expected to deteriorate on Tuesday afternoon.

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"This will see the fire spread to the east and south-east ahead of a southerly change that will see the fire move in a more northerly direction," the NSW RFS said in a statement.

"Firefighters are working to protect property and establish containment lines in the area supported by heavy plant machinery."

The RFS has urged people west of the fire to monitor conditions.

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A Corrective Services NSW spokeswoman said the jail houses around 120 inmates and has 50 staff.

Australian Community Media asked if inmates or staff would be evacuated, but the spokeswoman declined to provide an answer.

It is also unknown if smoke is currently impacting on the jail.

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"Containment fires took place over the weekend to reduce any hazards to the centre," the spokeswoman said.

"We will continue to monitor the situation and have well-established procedures in place to deal with any incidents.

"The centre also has an on-site Rural Fire Service division."

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