The warmest winter coats are typically those with a high-fill-power down insulation. These winter jackets are best for trapping heat and providing excellent insulation, making them ideal for colder climates. However, other factors such as the coat's material and design can also affect its warmth. For instance, if you’re looking for quality coats for the snow, go with options that feature water-resistant outers, longer lengths and a close-fitting design to help keep the cold out and the warmth in.