Uggs should not be worn in the rain or snow unless they have been treated with a water repellent. Getting untreated uggs wet can cause discoloration and damage the leather. Even when protected with a water repellent, be sure to dry them properly after use to avoid any potential issues.
Uggs are made of sheepskin leather, which stains easily. Snow and rain can cause small stains from the dirt that is in the water. The boots should be treated with a stain protector before being worn anywhere they may come in contact with dirt. Wearing them in the snow may also cause the leather to weaken and sag. In addition, wet leather has a tendency to smell bad. Sprinkling the inside of the shoe with baking soda may reduce some of the odor.