Yeah, the Arduino is 8 bit, but how often do you need to compute this? I geeked out and looked at the Steinhart-Hart Equation. Looks like computing (ln) is the worst of it and you only need to do that once in that equation.
It could be inconveniently slow, but even on the Uno, the docs I found on the Internet suggest around 30,000 float divides/sec. Multiplies are 3 times as fast. So, it might take a millisecond or two on an Arduino.
On other older microcontrollers, it'd be a lot slower though.
Thanks to OP for giving this PhD in CS something fun to research for the evening.