Imagine if your hair could change color depending on the temperature around you. Maybe when you walk outside, your hair turns blond, but when you go inside a grocery store, your hair turns red. It's not a Harry Potter movie, this actually exists in this world. It's called "FIRE" and it was just unveiled at London fashion week.

A company called The Unseen developed what they call "reactive fashion". The dye reacts to temperature and humidity, pretty much like a hyper color shirt from the 80s.

From wired.co.uk -

FIRE is designed to be responsive to temperature fluctuations, and is available in multiple colour ranges from bright red to subtle pastels. The data used to create the dye stems from the process of thermoregulation in the human skin and the colour change chemical reaction occurs in response to a certain stimuli - in this case, changes in the environment. When the temperature drops or rises, the carbon-based molecules at the core of the FIRE dye undergo a reversible reaction.

Check out the video below to see it in action.