Blonde hair is traditionally linked to light, openness and visibility. Dream books also read a change to blonde as a wish to be seen differently or to brighten your image.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.