If 'The Day After Tomorrow' comes...
Lol.. that's Monday! Jk.
I'll take you into some natural disasters or causes:
Global Warming: From the effect of greenhouse gases, it traps the heat that comes from the sun. Because of the sudden climate change, the compund rate is higher than expected. By 2020, part of India's low land areas will be under water due to icepoles mounting and increasing sea level.
Solar Dimming: A worldwide decline of 7% of light in the past 100 years. We won't need sunglasses in 50 years.
Earthquakes: Vladmir Keilis-Borok has been on a predicting earthquake project for 50 years. He is now 83 but recetly has been successful to predict major earthquakes in Northern Japan, setting of tsunamis and Central California, and Italy. He has been suspecting a large earthquake to come really soon starting with a 31000 sqaure kilometre shake in Southern California.
Tornadoes: Due to low and high pressure relationships, sometimes streaks of clouds will come down sucking up everything in its path. However there isn't any majors coming, the number of tornadoes repoted each year near the pacific and US has not died down.
Cyclone: Happens every year in my country. Due to heat rising, the cyclone border will slightly increase.
Volcanic Eruption: No major event, but many is likeli to be triggered in a shake.
Ice Age: Around 10,000 years ago the ice age ended, but it doesn't mean it's gone forever. For around the 17th Centuary in Europe, there is a mini ice age reducing the temperature by 5 degrees. This caused most lakes to freeze and many domestic animals to die.
Meteor Strike: Despite what many people have think, we do not have the money and experience to blow up a meteor. A meteor cloud may enter the atmosphere and we will die like the dinosaurs did. Every meteor is capable of doing about 1 Megaton which is the same as blowing up Hiroshima again with a Atomic Bomb.
Magnetic Storm: (Stareditron 4000 thought of this one

)I'll just quote what he said so I don't give false information.
QUOTE(Magnetic Storm from StarEditro's Post)
Uh, we've been watching Magnetic Storm in our physics class alot, so I think a Magnetic Reversal should be added to the day aftet tomorrow list. If that happens soon (hope not) alot more people will die from cancers, and many people will hurt...
So where will you hide?