PoserWorld has some cold-weather clothes for the kids. (The subscription, not the store. The subscription's a much better deal, anyway.)

There's also some skating clothing for the kids in the RDNA Christmas freebies, though they are rather old-fashioned looking.

The Japanese sites have free clothing for the kids, too.

http://digitalbabes2.com/~yamato/MilGirl.html

http://www5e.biglobe.ne.jp/~yagami/FSmain.htm