How hot is Azula’s fire? Well, blue fire is known to be between 2,600-3,000 F (1430-1650 C). But wait, there’s more!
Since Zuko was ~13 when he was banished, that would make Azula 11 at the time. I’m going to assume the flashbacks of Zuko Alone were a year before banishment, making her 10 there. At the time, her fire was a bright orange, which is around 2,200 F (1,200 C). Assuming Azula’s fire in the show is the hottest a blue flame can be (3000 F), then since she was 10, Azula’s fire grew 800 degrees in Fahrenheit (~430 C). Meaning it increased in temperature by 200 F (93 C) each year.
If this rate were to continue (which it probably wouldn’t), by the time she turns 50, Azula’s fire would be a thousand degrees hotter than the sun. I don’t think it would get that out of hand, because then she would die if she ever firebended.
Azula, when confronted with a giant wave thrown at her by Katara, is able to immediately evaporate all of it. She can slice buildings clean through when her aim is precise enough. These were both in the show. But what more?
I present to you: List of Things Azula Could Melt (easiest to hardest)
Fire Nation Battleship (Lego form) (ABS lego bricks melt at 221 F/80 C)
The jewelry she’s wearing in the first pic (assuming gold, 1948 F, 1064 C)
This loser (steel=2500 F/1370 C. gold mentioned above)
6. anything probably (clarification: anything under 3000 F melting point. Azula cannot melt: osmium, rhenium, tungsten, or carbon. Do not try this at home)