When buying boy's outerwear you want to make sure the jacket is proper warmth for the season. It is very easy to buy a jacket for the spring, summer, and fall. Fleece, sweatshirt and light nylon jackets for boys are readily available. In a pinch, a pull over sweatshirt will be fine.
Winter coats can be a bit tricky. When you are buying a boy's winter coat make sure you allow enough room for growth. Buying a jacket in the next larger size is a good idea in order to allow for a growth spurt. Buying big also allows you to layer a warm sweater or sweatshirt when it gets colder.