Brown spots, or hyperpigmentation, don't show up on just naturally freckle-prone people -- they can form on any type of skin during any time of year. But one thing is for sure: they tend to pop up most in the summer, when the sun's skin-damaging rays are abundant.

PHOTOS: How celebs keep their skin red-carpet ready

In the video above, Us Weekly asks NYC-based dermatologist Dr. David Colbert, who has treated the faces of Rosie Huntington-Whiteley and Rachel Weisz, how to prevent dark spots from appearing in the first place, plus what to do when a new one forms.

PHOTOS: Celeb-approved moisturizers

Dr. Colbert warns that if you see a new dark spot, or an existing one that has an altered appearance, head to your dermatologist to check it out. That kind of sun-care safety plus wearing SPF 30 daily (and reapplying it throughout the day) should help keep spots at bay.

VIDEO: How to fight body breakouts

To find out what kind of treatments are best at fading hyperpigmentation, watch the video above!

This article originally appeared on Summer Skin Fix: How to Fade Dark Spots