What Are Sun Dresses? What Are The Prevalent Styles In Them? What Are Sun Dresses? A sun dress is a casual or an informal dress that is intended to be worn in warm weather typically with a light-weight fabric. Commonly they are made up of cotton and are loose in fitting. They are available in different styles like bodice, sleeveless, wide neckline, shoulder straps and backless etc. They are typically worn without a layering top and are not worn over the blouse, t-shirt and nor with the leggings. While the word sundresses was first coined in early 1940s. They came into vogue in the year 1950s and after that became immensely popular.