How do I get rid of LITTLE BROWN SPOTS I get all over my arms when I go outside?

You know when you go outside in the sun and you get, like, these little brown dots that appear all over your skin? What's up with that shit? I go out for five minutes and later that night I notice little dot things forming on my upper arms. I get them on the right side of my face, too. I'm a fair skinned brunette, but wtf? I thought this only happens to gingers.