its takes a lot of energy to manipulate the nature. Energy is shaped and programmed by the mind. But everybody is a potential magician/occultist, many people are thinking: "the weather is too hot or too cold or too rainy". Your energy/psy-ball/spell must have inbued the necessary energy and clarity of instruction to bypass the mental chaos of untrained minds. This is why we meditate and other things.
In my experience nature/weather manipulation follows the natural order of things. If there is not enough clouds then it will take more energy and time while forming the "cumulus nimbus" if you want to experiment with this i recommend you what the wheather channel, if its monday pick a a probably sunny day like friday. Do the spell/ritual/energy work. days before so do give time to nature. Remember you have to program the energy, that is to concentrate on a clear and defined objective. Do it one time, when done try to not think much about it. (because you could reprogram the energy and it could fail)