Also, in regard to hurricanes and tornadoes an underground shelter or basement that will be protected might be important too

However, it's important to consider the types of weather problems your home and area are likely to have.

However, all that is changing a lot too everywhere. 

For example, in the last year we have seen many many atmospheric Rivers that can do a whole lot of damage very quickly in California especially along the coast from north to south with homes falling into the ocean as cliffs crumble slowly or quickly from the atmspheric rivers combined with big surf, high tides and the sea levels rising universally all over the world (not just in California but everywhere there there is a connected ocean. And since if you look at a globe or map that all the major oceans in the world are connected the water level (because of gravity) will universally raise the same amount world wide not just in California, Oregon and Washington but also all along the East Coast of the U.S. while Florida slowly becomes a series of Islands and places like Key West and parts of Miami are completely underwater pretty soon.

So, in a lot of more East Coast places I expect to see people tying up their boats and ships to the 2nd or 3rd stories of buildings in the near and far future. This is pretty inevitable worldwide wherever there is an ocean at this point.

Also, if you are going to build an underground shelter it is important to consider what your local Water table is doing so you don't have your shelter filled with water parts of the year also. However, there is always cement and rebar and swimming pool paint to make your underground shelter more waterproof like a submarine too.

As we were driving south from Santa Barbara the other day on business in Woodland Hills in the Lost Angeles Area of the state, I pointed out to my wife which sections of places like Oxnard and Ventura would likely be underwater in 20 to 50 years.

As storms get bigger and waves get taller because of increasing winds more erosion exponentially is going to happen everywhere. First the beaches all get washed away a lot in California during the winters by storms. Then next the water gets up to where there are cliffs along the California coast and then the water undermines the cliffs a lot and then the cliffs above the beaches often collapse and the soil then is washed out to sea. The sea during a storm becomes like a battering ram taking away all the beaches and then the cliffs and then any homes on top of the cliffs then fall down into the surf and beaches below and are destroyed. Each atmospheric river causes more homes and businesses to be red tagged and people aren't legally allowed to live there anymore from that point on.

And this sort of thing more and more is happening and will happen all over the planet wherever there are oceans that are connected worldwide.