Another day of extreme heat and fire danger is expected in Newcastle on Saturday, after which temperatures are expected to stay in the mid to high 20s until Christmas Day.
The Hunter sweltered through a day of extreme heat on Thursday before a southerly change was due to bring relief.
Air quality was rated hazardous in Newcastle on Thursday, as strong north-westerly winds brought bushfire smoke that obscured visibility.
The Hunter's hottest temperature was recorded at Tocal, where the mercury rose to 42.2 degrees.
Nobbys hit a high of 38.9 degrees, while Williamtown recorded a top temperature of 41.1 degrees.
Don White, of Weatherwatch, said the southerly change would lead to milder weather on Friday.
A high of 38 degrees is expected for Newcastle on Saturday, while the mercury is forecast to soar to 46 degrees in the Upper Hunter.
"We're looking at temperatures into the high 30s again [in Newcastle] on Saturday before a south-easterly develops for a few days. That should keep temperatures down to the mid to high 20s through to Christmas Day," Mr White said.
The escalating bushfire crisis prompted Premier Gladys Berejiklian to declare a state of emergency across NSW for seven days.
It also prompted the government to close state forests for the Christmas and New Year period.
In the Hunter, forests at Chichester, Barrington Tops and the Watagan mountains will be closed, meaning numerous free camping areas - where many people usually stay over the holidays - will be off limits.
Picnic areas, walking tracks and lookouts will also be out of bounds.
The decision was taken due to bushfire risk and expected heatwaves, Forestry Corporation of NSW tourism manager Louise Faulkner said.
Police will patrol visitor areas in the forests to alert people they are closed.
"It's not about enforcement, it's about making sure everybody knows," Ms Faulkner said.
"Even though we all know there's a fire situation, people might not necessarily know their favourite annual forest spot is closed for Christmas."
She said the forest closures were about safety.
"If a situation emerges and fire happens very quickly, given that a lot of our staff are fighting fires in other areas, it may be very hard to have the type of response we normally would to help evacuate visitors," she said.
NSW national parks haven't been subject to the same kind of blanket closure.
"While a number of parks in NSW remain open, these can be quickly closed at short notice in forecast dangerous weather conditions," a National Parks and Wildlife spokesperson said.
"For specific parks that are closed, check our alerts page."
