At the salon, when your hairdresser starts to wash your hair, she'll usually check and ask if the water is OK for you, and she'll adjust it to suit you. While it's true that when it comes to washing their hair, some people prefer the water hotter, while others prefer it colder, in fact, the ideal temperature is somewhere between the two extremes, and it's best to wash your hair with warm water.
Why warm water? If the water is too cold, it won't eliminate the excess grease, while if it's too hot, your scalp may react by producing extra sebum. Warm water allows for efficient cleansing without aggression and irritation to your locks and scalp.
What about rinsing? Once you've washed in warm water, it's a good idea to use cold water for the final rinse, as this will help to close the cuticle, leaving your hair looking glossier as it reflects the light better.