What you describe is the ability to tune into energy. In your case, it manifests in being able to influence weather. Many other people describe their psychic gifts. But... unless you are born into a family that practices witchcraft, i.e. actually lives it, then you aren't a witch. A witch is a human being who does witchcraft. People need to separate the two things out... psychics (and energy workers) can be witches, and witches can be psychic but those things can also be exclusive. They are not automatically connected. Someone can be a witch and not have any discernible psychic gifts at all. Over time, they usually develop some witchy skills because that's how it goes and everyone can learn to use their intuition or how to cast spells.
In your case, if you decide that you want to be a witch, then you can. The study, broaden your knowledge, practice your skills, learn about the history of the craft, set up an altar, have a go at divination, carry out some rituals, observe the Moon and Earth cycles, connect with nature, etc., etc., and then you will be a witch.