you mean conjuring snow like in Frozen? no, cannot happen.
make it snow in July, also impossible depending on your location. if its winter and you are in an area that gets snow, you might be able to. weather spells are a grey area for most people, it works with natural forces, but its also playing god. remember you are not creating snow in this instance, you are moving whole systems of weather to make yourself happy. this could cause natural disasters in other parts of the world.
historically speaking there are tales of people casting weather spells, like when there was a drought. there's an old knot spell that sailors use to use, each knot held wind, one stronger than the last, as you untie each one the wind would pick up. if all were untied however, a violent storm would appear. don't know if these are true, neat stories though.