The fire started in the Coalfields scrub near Abermain on Thursday afternoon and spread to the suburbs of Kurri Kurri, Abermain, South Weston and Pelaw Main.

Within hours of the first alert, NSW Rural Fire Service volunteers were on standby to defend Kurri Kurri hospital as it was evacuated and the flames approached.

Five homes were destroyed in the fire, along with a dozen other buildings including Teasdale's Tyres. Another 11 homes were damaged.

The fire has been brought under control, with containment lines shored up by late Saturday afternoon. But firefighters were on the fireground to continue blacking out and mopping up, NSW Rural Fire Service chief inspector Ben Shepherd said yesterday.

"They held it through yesterday's weather, but there's still a bit of work to do each day just to make sure it doesn't spread any further," he said.

"There is some bad weather coming through on Tuesday, when we will see the return of hot and windy conditions again but the good news is, it's contained."

The fire held behind containment lines was likely to continue to burn for a number of days, Inspector Shepherd said.

The impact of the fire had been significant, he said, and the message this fire season was that fires did not have to be massive to pose a threat.

"Primarily, the areas that didn't burn through 2019-2020 were close to some of the most significantly populated areas ... in the Hunter, Central Coast and in and around Sydney, where we had fires on the outskirts but it did't necessarily come into bushland near suburbs and this year, that's where we're warning the threat could be.

Residents have been advised to monitor surroundings for ember attacks. Authorities are yet to determine how the blaze started.