You probably already know that the area closer to a nuclear bomb when it blows up, the worse the damage will be. Experts have made diagrams and charts telling us things like how far away you need to be to avoid having your eardrums blown out, for example. You have to be very close for that to happen, you may be relieved to know.
The furthest out immediate result is a burn that is equivalent to a bad sunburn. At maximum range for these burns, it will occur only on exposed skin. Something as simple as duck and cover is enough to protect you from this and other hazards. You have only seconds to duck and cover to protect yourself between the flash of the explosion and the other more dangerous effects reaching you. If you realize what the flash is and react immediately, you can avoid a lot of the potential damage to your body.
If nuclear alert sirens are activated while nuclear missiles are still in the air, you will have more time to take good shelter before detonation.
One of the effects of a nuclear weapons detonation in the air is called an electromagnetic pulse, or EMP for short. I have already posted on EMPs earlier. I will explain it again here, with the short version. What you need to know about an EMP is that it will destroy electronics. That includes all vehicles less than 30 years old, most household items that include electronics, and commercial, industrial, and military electronics. That will include most, if not all power plants in the USA.
The USA is not very well prepared for EMPs. Some effort has been made to prepare for them, but those efforts are based on EMPs that are much smaller than modern nuclear weapons will generate. That means the things protected against smaller EMPs, than the one that hits them, will be wiped out anyway.
Areas that are not hit by the EMPs will still have working electronics. That means if you have a radio that is protected from EMPs, you can take it out after the EMP hits your area, and listen to broadcasts from outside your area. After a nuclear disaster, information could be especially crucial to your survival. Having a radio that is protected from EMPs might save your life some day.
The size of the nuclear explosion changes the size of the area affected and how far away you need to be from it to avoid various kinds of injuries. If you wish to have or prepare a shelter for nuclear disaster preparedness the size and closeness to the blast will affect what materials you want in your shelter and how thick it needs to be to protect you.
There are handy charts on the internet that say how thick your shelter walls need to be depending on what kind of damage you wish to shield against and how close you are to the blast.
We can make educated guesses about the most attractive targets for an enemy nuclear weapon or multiple nuclear weapons for the most attractive targets.
If you live in a country that has nuclear weapons and is prepared to use them, you probably have enemies of your country that have nuclear weapons also. Most likely the other country or countries that have nuclear weapons to use against your country will pick certain types of targets over others. Examples of these attractive targets are government centers, military and weapons centers, and manufacturing and financial centers.
If your residence is near one of these type of centers, you can either move, or make yourself a shelter. You could also do my personal favorite, move and make yourself a shelter.
I intend to post about the damage done at various distances from a nuclear disaster. I plan to provide both diagrams and charts and will give both miles and kilometers. I expect to do an entire post on terrorist detonation of a nuclear weapon. They are different than most other nuclear disasters.