Typically, no. Winter sports helmets are designed a little bit differently to protect little ones from the dangers they can face while on the slopes. Wearing a bike helmet while you’re skiing might provide adequate enough protection but we would suggest either investing in a snowsport-specific helmet or else renting one when you get to the slopes just to be on the safe side. These helmets are typically warmer for the cold weather you will encounter and your little ones might find the ventilation from their bike helmet to be too chilly to wear in snowy weather.