Weather magick does not work that way. You can only influence the weather, not control it. Of course this is to the ones that actually believe that they can influence the weather, to the ones that do not think they can do it at all. Weather magick is a biased topic.
It may have been a coincidence but I once used a snow sigil and later that year I got snow, and we rarely get snow but saying this it was probably a coincidence
Intention has a lot to do with magic as well. Such selfish ways shall not be answered by simply muttering a few words and wala, you got snow. Magic in its essence is quite unstable and takes many years to learn. Don't expect to be master of the elements in a few days, or even a few years. Aim for smaller goals, do your research and meditation, and for the love of god check out newbie central.
Unless you either have no guilt or do not consider it selfish. A few years ago I performed a snow spell to get out of school. It wasnt very wise messing with the weather and i see that now. but, the point is muttering those apparently seemingly pointless words did in fact work. Should someone new to magic cast a weather spell? Well thats entirely the oppinion of the individual.
Do you even understand by tampering with the weather you may cause devastation to your own region but to others as well, Weather is a delicate balance, by throwing the balance out of whack means that there is consequences not just for you but for the very environment. What is to stop your "simple snow spell" from becoming a blizzard and killing people, hmmm. My point is think before you touch the weather like maybe suck it up and just go to school.
I do know how irresponsible it is and in no way am i attempting to say you`re wrong in that aspect. Im just saying sometimes you have to learn by experience.