Why Does Pigmentation Become Worse During Summer? Summer Is the season when many people notice dark patches, tanning, uneven skin tone, and dullness on their skin. If you are wondering, Why Does Skin Pigmentation Increase in Summer?, the main reason is increased exposure to harmful UV rays from the sun. https://sites.google.com/view/drnikitapatel/blog/why-does-skin-pigmentation-increase-in-summer