Hyperpigmentation or the darkening of patches of skin caused by increased melanin (i.e. too much time in the sun) is common after the summer season. Instead of trying to eliminate hyperpigmentation at the end of summer with expensive in-office treatments or prescription medications, prevent it altogether by avoiding the sun, wearing a hat, and using appropriate sunscreen. Dr. Pfeifer suggests using one with an SPF of at least 30 and reapplying it every two hours or using a mineral powder SPF such as Colorscience, which does not need to be reapplied as often.
You can also try a daytime protection cream, like Repechage Biolight Brightening Protection Cream, which contains zinc-oxide, a mineral sunscreen. And don't forget clothes and swimsuits that have built in sun protection such as Parasol and HydroChic. Protecting your skin now will save you tons of money in the future!