My son will play outside much longer when he's warm.  These boots are great for sub zero temps and holding up to daily wear and tear, plus they're easy to get on and off.  The last time I bought this brand the sales person recommended I buy one to two sizes up, which allows for a thicker sock, makes getting them on and off easier, and (the salesperson claimed) is better for warmth.  I'll definitely buy another pair of Kamik's when he grows out of these.