To dream that you have a sunburn, indicates that there is an emotional situation or problem that you can no longer avoid. There is some urgent matter that is literally burning through to your soul and demands your immediate attention.
Dreaming you have a sunburn when you don't can mean you feel you've exposed yourself too much to the negativity of the world, or that negativity from others is getting you down. It can mean you're irritated about others trying to cross your boundaries or take advantage of you. Or it can mean you're feeling like you've been "burned" by someone.