A woman is dead, three people are in hospital and 20 people have been evacuated after a series of house fires in NSW.

A woman’s body was found at the scene of a house fire in Wollongong about 2.30am (AEDT) on Thursday, Fire and Rescue NSW Superintendent Ian Krimmer said.

The cause of the fire and death is being investigated.

Earlier, a woman and two children were taken to hospital with smoke inhalation after a fire in the western suburb of Wentworthville.

Firefighters were called to the house at 12.10am and contained the fire at the front of the house.

In a separate incident, seven people were evacuated after a fire broke out at Macquarie Fields in southwest Sydney at 9.45pm on Wednesday.

A further 13 people were evacuated after a blaze started on the second floor of a unit block at Granville in western Sydney. No injuries were reported.

Still in the west, a vacant house at Blacktown was also extensively damaged by a fire.

“It has been an unusually busy night,” Supt Krimmer told AAP.

“We have a number of house fires being investigated.”

A cold snap overnight and the use of heaters may have contributed to the blazes but it was too early to say, he added.

Firefighters also fought a blaze at a waste transfer station in Homebush, with 30 personnel working to bring it under control.