Yes, that's fair, but you have to be careful what physical characteristics you're talking about (don't forget all those black African pygmies), and be sure to not include any behavioral characteristics.
Instead of races scientists use
clines. However you still can't make speculations about one trait based solely on the existence of another trait. Geographical cline maps for even skin color are pretty surprising. There is a correlation between nearness to the equator and skin color, but it's not absolute. For example, Eastern native Americans had lighter skin than Western Native Americans.