Does the sun really have an impact when it comes to lightening my hair naturally? If so, does this mean I can skip my coloring appointments in the summer?
Summer should not alter your maintenance routine. If you are due for a highlight appointment and want to look your best, keep them up as you would any other season. Unless you spend an excessive amount of time in the sun (and even then it will just bleach your ends) your highlights won't significantly lighten just from the warmer weather.