You use SPF on your skin to protect against cell damage and premature aging. You need to do the same for your hair.
According to haircare experts, your hair needs sunscreen to stop:
Fading - sun exposure (UV rays)  bleaches natural and colored hair
Yellowing - sunlight can turn grey hair yellow
Brassy tones - your blonde and highlighted hair can turn a red-orange color
Dry, brittle hair - heat and sunlight damage and roughen your hair shaft
Premature greying - UV rays can cause irreversible loss of pigment
Arey leave-in-conditioner Live In Mist contains an effective, plant-based sunscreen.