I bought this suit for my 9 month old, but ordered the 18 month size after reading other reviews.  I am glad I did.  It is big, but not as much as I expected.  The material is like a down jacket, so it's not great at being waterproof, but my son is small enough that he isn't playing directly in the snow, so it's not an issue (yet).  This may not be the best fabric if you have an older child that is going to be sitting or crawling in the snow.