With around 15 thousand nuclear warheads in the world, what happens if we have a nuclear war. And more importantly what would happen if a nuclear weapon was dropped near you?
A lot has to do with the yield, and whether it was an air burst or a ground burst. ASAP science goes into the details on geographical layout and the design of the building in which you are located.
If a nuclear bomb explodes about 35% of the energy released comes in the form of thermal radiation since thermal radiation travels at about the speed of light the flash of light and heat comes several seconds before the blast wave. Given a 1 Mt bomb those up to 21 km away would experience flash blindness.