Well that's impressive, but I don't know exactly what temperature it would scale to, I mean burning a person until they turn into char, from what I remember it's around 900 degrees Celsius.
I have seen in Avatar examples of firebenders melting iron that is a temperature greater than 1500 degrees celcius, this is without considering that in the work there are several examples of firebenders capable of using lightning that reaches 30,000 degrees Celsius, so it wouldn't be exactly unexpected that the high-ball temperature of firebending is around that (Of course, I'm not an expert in avatar profiles to say for sure, but I think it's likely that it scales to that temperature)
So from what I know, she doesn't resist the full temperature of firebending.