"The metric system measures more than just length, and Celsius temperature scale has always been a part of it."
Indeed, it also measures area and volume - derived units - as well as mass. It's even been extended to encompass time.
It does not cover temperature however.
"Actually, Celsius is part of the SI Units, it is specifically referenced in the SI as a 'coherent derived unit'."
*sigh* Right, don't let me stop you from patting yourself on the back. Pretty much everything is recorded in SI, if for no other reason than conversion and comparison.
Celsius is not the base unit for temperature in SI however, Kelvin is.
In any case my original point seems to have gotten lost in the rabid needs to debunk my post - Celsius is not a metric unit.