Over a period of several years I've had these weird dreams of different types of disasters happening. Their are four primary types of dreams:

1) Water dreams. They usually revolve around excessive rain causing a flood or a giant wave coming from the ocean that I see coming but that I know I don't have time to escape from. I don't live near any ocean, but in these dreams I am usually in my house and right near the ocean.
2) Tornado dreams. Dreams. About tornadoes.
3) Animal dreams. Not really a "disaster", I guess, but I'll add it anyway. In one dream, a bear on the loose entered my home through an open patio door, and I had to rush to find a way out. In another dream I lived in a house in the woods that for some reason didn't have a real roof, but instead had a roof that looked like a fence. Several cougars climbed up on the fence/roof and started trying to get in. They eventually ripped a hole in the roof and started dropping down into the house.
4) Nuclear bomb dreams. I've had this dreams a couple times. I'm sitting on the couch and I can see out through my patio window. I see a mushroom cloud rising in the distance, and after a few seconds the shock wave hits.

I always wake up from these dreams with my heart racing, disoriented for a moment. I typically can't get back to sleep after one of these dreams, even if it's only, like, 4 am.