It's a little crazy to think about snow when it isn't even officially summer! But I have this Columbia Bunting Snowsuit that Olive wore last winter in my closet ready to go!
http://www.amazon.com/Columbia-Unisex-baby-Infant-Snuggly-Bunting/dp/B0090NILKO
It is awesome because you can completely cover their hands and feet, or you can let their hands and feet stick out. It's very warm and perfect for little ones to play in the snow!
The size is 18 months, but I think it runs a little small. Olive is on the taller side (75%), and she definitely couldn't have fit into it with the foot cuffs on at 18 months, though it would have fit without the cuffs. So I think it is best for babies that are 12 months when it is snowing.
Retails for $45, asking $20 with shipping included in the price.