An 800 hectare fire continues to burn wilderness in the Kosciuszko National Park, near Khancoban in southern NSW however fire fighters are hoping to complete containment lines to control the blaze.
Fire fighters are particularly worried by extreme temperatures estimated to reach the high 30s and low 40s in some parts of the state today.
No other major fires are burning, but fire fighters say today's conditions could make any new fires difficult to battle.
"The issue today is just what the weather is going to bring," NSW Fire Brigades spokesman Cameron Wade said.
"High temperatures and low humidity, which we also had yesterday, but today we're going to have wind with it as well - that's the three components that causes most problems."
"If a fire was to start, it would be extremely difficult to control," he said.
Temperatures could hit record highs across the state, with the Bureau of Meteorology forecasting temperatures in the low 40s in central and north-western parts of NSW.
Sydney's record temperature for October is 38.2 degrees Celsius, with the mercury expected to reach 37 degrees today.
"There is some chance we'll beat that," said senior forecaster Neale Fraser.
The bureau says hot winds are coming from the north-west at 30kph, while a southerly change is making its way through the state's south-west in the Riverina area.
This will reach the South Coast in a few hours and is due to hit Sydney between 7pm and 9pm and is expected to cause a dramatic drop in temperatures.