Why do I keep having nightmares about natural disasters?

For a few months now I keep waking up in the middle of the night sweating and with my heart racing. I've recently started to notice that all of my nightmares have been related to natural disasters. The worst ones so far have been about extremely violent and fast tornadoes. I don't know why I'm so scared of tornadoes though as I live in the UK where they are very, very rare. I've never even seen a tornado in real life before. I also keep having nightmares about tidal waves and mass floods. The dreams are so detailed that I actually feel scared typing about them right now as all the images are coming back in my head.

Anyway, why do you think this is happening to me? I've literally never been involved in any kind of natural disaster. Do you think a serious one might be about to happen and I'm the messenger to everyone?? Sorry if I sound insane but I'm absolutely terrified.