So long as your little ripper is dressed for whatever Mother Nature happens to throw your way, you can still have fun in the Great Outdoors with a minimum of whining. This goes double for family climbing trips, where frigid mornings, stormy afternoons, and mud puddles are all commonplace.
Ollie and Stella Children's Outfitters' Ducksday Rainsuit is by far the most versatile and elegant solution we've found so far. The waterproof and windproof one-piece is easy to get on and off, and has a hood and stirrup feet to keep noggins and toes dry. For cold days, a one-piece fleece midlayer (sold separately) adds warmth without adding bulk, and can be worn separately for dry-but-nippy weather.