FIRES burning across NSW have been downgraded to advice level as cooler weather and rain sets in.

NSW Rural Fire Service (RFS) Brendan Doyle said the fires burning in the state are no longer threatening any homes or properties

"They are all at what we call advice level," Mr Doyle said.

"We have 51 fires in the state of NSW, only 13 of them are remaining uncontained.

"It's very much a welcome relief, this cooler weather.

"We're hopeful that this rain will be widespread and it be actively directed to these firegrounds to give our firefighters a well-earned rest.

"We're waiting for these cooler temperatures and the potential for rain over the next four days to really assist those crews."

The fire in Kemps Creek, in Sydney's west, has improved with overnight conditions and some light rain, the RFS says.

But more than 500 firefighters and 40 aircraft are still on firegrounds across NSW helping put out blazes.

"We have a lot of work to do, there's still a number of large fires still burning," Mr Doyle said.

Originally published as NSW fires no longer threatening homes