The fire ripped through more than 5000 hectares at Heatherbrae, Tomago, Williamtown, Campvale and Medowie after it broke out on Sunday, October 13, and flared up again on Thursday to become "out of control".

In addition to eight buildings destroyed, another 12 structures [including homes] were damaged, the airport closed, arterial roads cut off and hundreds evacuated from their homes.

Port Stephens crime manager Inspector George Radmore said he condemned the actions of those responsible for any bush fire.

"It is very disappointing to think that anyone, let alone young people, could be involved in such a serious act in such weather conditions prevailing at that time," Inspector Radmore said.

"Seemingly innocent actions can have serious ramifications for the community and the future of the young people in relation to criminal histories."

Port Stephens detectives and officers linked with Strike Force Tronto arrested the 11-year-old on Monday morning at his Raymond Terrace home.

He was charged with two counts of intentionally causing a fire and being reckless about its spread. Police will allege he lit two fires on October 13 - a grass fire in Raymond Terrace, which was extinguished, and the Heatherbrae fire.

The boy briefly faced Raymond Terrace Children's court on Monday when bail was refused and he was to appear in Broadmeadow Children's Court on Tuesday.

A 15-year-old was arrested on Monday afternoon in relation to the Heatherbrae fire. He was charged with intentionally causing a fire and being reckless about its spread. He was granted conditional bail and will appear in Raymond Terrace Children's Court on November 20.

Inspector Radmore said the charges of intentionally causing fire and being reckless about its spread carried a maximum of 14 years imprisonment.

Lower Hunter Rural Fire Service manager superintendent Jayson McKellar said the fire was contained but firefighters were braced for hot, windy conditions.