As a cooler change blows into Sydney, much of NSW is facing the most catastrophic fire danger in history as a monster hot air mass continues north.
While temperatures aren't even tipped to reach 30C in Sydney on Sunday, much of NSW will remain above 40, as fire dangers reach unprecedented levels.
"To put it simply, they're simply off the old conventional scale," Rural Fire Service Commissioner Shane Fitzsimmons said on Saturday.
"It's not another summer day, it's not another bad fire weather day. This is as bad as it gets."
Catastrophic conditions are forecast for the Greater Hunter, Central Ranges and North Western area.
Towns in northern NSW are set to cop the brunt of the hot air mass moving north towards Queensland.
Tamworth is forecast to reach 44C and Moree 46C, while Walgett and Bourke could reach a sweltering 47C.
Firefighters were battling a bushfire east of Dunedoo, on Saturday night, prompting a watch and act alert for residents of Uarbry and Cassilis.
