Yeah, that's the sort of thing I was talking about with my comment about dynamic range and resolution. A 10 bit ADC is somewhat limiting.
A filter cap will cost you all of $0.10, but whether or not it's necessary is a function of the amount of noise in your circuit. If you're just driving a voltage divider with a DC voltage, it shouldn't be too bad.
If I were doing this and wanted to avoid the low temp jitter, I'd just ignore anything below like some temperature like 100C and display "low".