Babywearing can sometimes seem intimidating at first, but it can feel even more intimidating when considering hot or cold temperatures. You can babywear in any climate, but it takes some research ahead of time to feel successful and comfortable. I actually suggest babywearing in winter since your baby carrier counts as an extra layer for your baby. Your body heat also keeps your baby safe and cozy, and gives you constant supervision and bonding with your baby. Not to mention, easy access for breastfeeding and keeping baby healthier through cold and flu season. All good things!
Here are some guidelines for what baby should wear for outdoor winter babywearing:

Cool Weather, above freezing:
Base Layer -- Long sleeves, Pants, Socks
Hat & Mittens
Fleece Outwear -- I love the Cozy Elf Suit from Zutano!
Cold Weather, below freezing:
Base Layer -- Long sleeves, Pants, Socks
Second Layer -- Wooly Sweater, Pants, Wooly Socks
Hat & Mittens
Fleece Outerwear
Cold Weather, below freezing, with precipitation:
Base Layer -- Long sleeves, Pants, Socks
Second Layer -- Wooly Sweater, Pants, Wooly Socks
Hat & Mittens & Legwarmers
Waterproof Insulated Snowsuit -- The ones from Patagonia are great!
Coldest Weather, frigid cold with or without precipitation:
Base Layer -- Long sleeves, Pants, Socks
Second Layer -- Wooly Sweater, Pants, Wooly Socks
Hat & Mittens & Legwarmers & Fleece Jacket
Waterproof Insulated Snowsuit
Always remember to dress your children under two years old in one additional layer than what you would feel comfortable in. Lucky for babywearing in winter, your wrap, sling, or structured baby carrier counts as an extra layer.
** If you have a walking child, my favorite boots for bitties are from Bogs!