Snow, bushfires, then snow again in NSW

Snow one week, bushfires the next.

Then potentially more snow.

NSW is in the midst of some erratic weather.

Firefighters are still battling to get a bushfire under control in the Blue Mountains, but just two weeks ago, the same area was blanketed in snow.

Now forecasters are predicting snow could return even before the blaze has been fully extinguished.

Just last night, the temperature in the Blue Mountains dropped to -1C.

It's an odd series of weather events, but not as improbable as many would expect, say experts.

"It seems to be hard wired in our brains that high temperatures equal bushfires, but it's not the case," Professor David Bowman, from the University of Tasmania, told AAP.

"The real take home (message) with the Blue Mountains fire is that if you have dry fuels and high winds, you can have fires at any time of the year."

NSW RFS Deputy Commissioner Rob Rogers says it is unusual to have to deal with a fire of such intensity during the colder months.

"Because the weather was so dry, and the fuel's there, it (The Blue Mountains' blaze) was difficult," he said.

Crews have spent more than three days trying to contain the fire that began at Wentworth Falls on Friday night.