"When it's cold outside, there's hardly any water vapor present in the air, whereas boiling water emits vapor very readily that's why it's steaming," Seeley says. "When you throw the water up in the air, it breaks into much smaller droplets, so there's even more surface for water vapor to come off of.
"Now, cold air is very dense, and this makes its capacity to hold water vapor molecules very low. There's just fundamentally less space for the vapor molecules," Seeley explains. "So when you throw the boiling water up, suddenly the minus 22 air has more water vapor than it has room for. So the vapor precipitates out by clinging to microscopic particles in the air, such as sodium or calcium, and forming crystals. This is just what goes into the formation of snowflakes."
that was from some science page, but every time i did it in Mn. it just looked like it turned into steam, i assume because the crystals are so small.