[Uhhh...]

I guess mind control would be possible, but I don't think brainwashing and controlling the weather correlate.

Let's say that they have a machine that can do that. It can control the weather. It would be much easier than mind control as they are controlling one aspect. I mean, the weather seems to be a constant all around, so I'm going to assume that the weather is one entity. It's a large entity, but that's more of a power issue than a complexity issue.

But if you want to control minds, you'd need a fairly complex and powerful machine. We all think on different wavelengths and we're all individuals. It would take a lot of power to be able to control all our minds. It would also have to take in account of everyone's thinking patterns, so this machine must be very complex.

At least, that's what I'm assuming would be the case, but maybe it's possible they can easily control us! But that would require a lot of research in the weather patterns and we'd need concrete evidence that the weather is being controlled by them to prove your hypothesis.