Lab’s have a Double-Coat, meaning they have two layers of fur: a top layer called the Guard coat that is the more “wiry” hairs. Then underneath you’ll find a softer and lighter under-layer called the Undercoat, which is that fluffy stuff they shed. These layers combined are used to regulate body temperature, protect from harmful UV rays, repel water, and protect their skin.
The undercoat is an amazing insulator, and it keeps them warm in the colder months. But those layers of fur also keep them cool in the summer, and insulate them from warm air.
Pretty clever hey!