What is Color temperature?
The warm-cool axis of a color or a light source, measured in Kelvin (K). Lower temperatures (2700K) are warm/orange; higher (6500K) are cool/blue. Affects color matching across viewing conditions.
In detail
Color temperature describes whether a color or light source appears warm or cool. Tungsten incandescent light is ~2700K (warm orange-yellow). Daylight at noon is ~5500K (neutral). Overcast sky is ~7000K (cool blue). The same fabric color looks different under each light source — a coral that reads vibrant under daylight reads muted under tungsten. Production color matching standardizes on D65 (6500K daylight) viewing booth conditions for this reason. Pantone TCX swatches are calibrated to D65. Designers should preview their work under D65 lighting before sign-off.
Example
A swimwear coral matched to TCX 16-1546 looks vibrant in a designer's daylight-lit office (~5500K). The same swimwear hangs in a retail store under warm spotlight (~3000K) and reads orange-shifted, almost terracotta. The store's lighting is the problem — the dye is correct.