Warm color can be translated "暖色（dan-syoku）", and cold color will be "寒色（kan-syoku）". And actually, you may also say "あたたかい（暖かい）色" and "つめたい（冷たい）色", they are both applicable :)

Yes you can Apply あたたかい or つめたい to describe colors. If you want to mention a group of colors You can also say 暖色系 = warm 寒色系 = cold So warm blue and warm yellow would be あたたかめの青 or 暖色系の青 for warm blue あたたかめの黄色 or 暖色系の黄色 for warm yellow Hope it would help