At least according to this guy:

For ice crystals to form, producing more order, heat must be extracted from the local system and added to the surroundings, or the surroundings must be made more disordered in some way. The agent for causing this ordering of a local system and disordering of the surroundings is the immediate or secondary result of an action by an agent separate from the system. This agent must do work to remove heat energy from the pre-coded structure of the water molecules and their associated hydrogen bonds.

Whew...and you already thought god was busy answering all those prayers to save kittens and win baseball games!

Or, you could, like, read a real scientist's explanation:

Conversely, why do snowflakes form when moisture (water) is in air that is colder than water's freezing temperature? If energy can readily spread out, it will. That is the second law! Therefore, if something is warmer than something else and the two are in contact, the warmer will spread or dissipate some of its energy to the colder. This is why the water will disperse its energy to the colder air and then the water's temperature will drop to freezing and the water will begin to form crystals of ice that we recognize as snowflakes. (Water molecules in air form snowflakes, ice, in hexagonal patterns because the energies in that shape of crystal are lowest — a greater amount of energy will be dispersed as per the second law if those hexagonal patterns are formed rather than other possible forms.)

Hmm...which explanation to choose? One, a supernatural agent personally interacting with each raindrop and sucking heat energy from it so that it will form into a proper snowflake, or that the energy dissipates from the water into the colder air, resulting in a crystallized shape that consistent with the lowest energy state.

Actually, they both sound pretty reasonable, huh? Maybe we should give equal time in the classroom to the Intelligent Crystal Formation crowd.