Thunderstorms are set to strike after scorching heat and dangerous fire conditions swept across eastern Australia.
But authorities have warned it may not provide much relief, with another possible fire threat looming - lightning.
A cool change is expected after some regions sweated through heatwave conditions, with temperatures pushing into the mid-40s.
It prompted a severe thunderstorm warning for northwest NSW, with possible damaging winds, large hailstones, heavy rainfall and flash flooding.
The Bureau of Meteorology warned Gunnedah, Narrabri, Wee Waa, Baradine, Mullaley, and Boggabri to be on high alert late on Friday.
However it warned the forecast storms may spark more fires across the state.
"Many of the thunderstorms will contain little rainfall so there's a risk of new ignitions," the bureau's Stephen Stefanac told AAP.
"Thunderstorms could also produce strong to possibly damaging wind gusts, which would create challenging conditions for firefighting crews on the ground."
Lightning has already sparked fires throughout NSW, with almost 70 blazes reported by late Friday.
The NSW Rural Fire Service said none are currently of significant concern but warned there were total fire bans in place in the Northern Slopes, North Western, Greater Hunter and Greater Sydney regions late on Friday.
Northern Slopes in the only NSW area with a total fire ban in place for Saturday, it said.
Since Christmas Eve, hot, dry, and windy conditions have been building across eastern Australia, intensifying bushfire risks.
Victoria’s Grampians National Park is one of the worst impacted, with a massive blaze burning through approximately 74,000 hectares.
Sweltering temperatures and wind gusts up to 95km/h have complicated firefighting efforts in the iconic region.
A dramatic cool change brought some relief to the Grampians on Thursday night, dropping temperatures by 10C degrees in two hours.
But it offered no rain, leaving firefighters to battle the inferno under challenging conditions.
The extreme weather has also pushed up temperatures in other parts of the country.
Birdsville, in southwest Queensland, recorded 47.2C on Boxing Day, the nation’s highest temperature, while Moomba in South Australia reached 45.5
Western Sydney faced extreme fire danger, with temperatures soaring into the low 40s, while coastal areas recorded highs in the upper 30s.
"With that heat and also very dry winds coming through from inland areas, we are expecting extreme fire dangers for Sydney, Hunter and the northwestern slopes of NSW," said the bureau's Jonathan How.
Queensland was also feeling the heat, with Brisbane expected to peak at 37C on Saturday and up to 40C in its western suburbs.
The bureau warned of "low to locally severe intensity heatwave conditions" along Queensland’s east coast throughout the weekend.
Relief is on the way for southern states, with temperatures in Victoria and South Australia expected to drop by 10 to 15 degrees over the weekend.
Melbourne and Adelaide are forecast to enjoy much milder conditions, with highs of around 22C on Friday.
Authorities urge residents to stay updated on weather warnings and follow advice from local fire services, as volatile weather conditions continue to affect large parts of the country.
