Most people think of red as a "hot color" and blue as a "cold color". This is, of course, completely wrong from the thermodynamical point of view. All astronomers and photographers known that. However, even the later still call the R and B sensor pixels as "hot" and "cold" ones sometimes, instead of vice versa.
The confusion is probably from the fact that people have only seen relatively cold objects, like the sun or a light bulb, which are just a few thousands of ºC.
So, it's suggested that from now on we refer to them as "hot" and "very hot" to avoid confusion. And by the way, pink is both hot and cold, and green is neither.