Depends on if you buy an insulated or shell ski jacket. Insulated jackets have built in insulation and some jackets like 3 -n-1 jackets the insulation you can zip out. Insulation is measured in grams and the higher the number the warmer the coat is. Shell ski jackets just have an outer waterproof breathable layer with no insulation. Most people layer up with Shell jackets and shed the layers if they get too warm. If you get hot easily then Shell ski jackets are for you and they also give you more mobility.