Religion can help you here.
Let's start by quoting a pertinent What if
They say lightning strikes the tallest thing around. That’s the kind of maddeningly inexact statement that immediately sparks all kinds of questions. How far is “around”?
There’s a cool trick for this, and I’ll give it away right here at the start: Roll an imaginary 60-meter sphere across the landscape and look at where it touches.
To figure out where lightning is likely to hit, you roll the imaginary 60-meter sphere across the landscape (for safety reasons, do not use a real sphere). This sphere climbs up over trees and buildings without passing through anything (or rolling it up). Places the surface makes contact—treetops, fenceposts, and golfers in fields—are potential lightning targets.
This means you can calculate a lightning “shadow” around an object of height h on a flat surface. Now, that doesn’t mean you’re safe on the ground around it—often, it means the opposite. After the current hits the tall object, it flows out into the ground. If you’re touching the ground nearby, it can travel through your body.
Now that you got an empirical way to find the risky place, let's say that your religion demands that those places are sacred to the gods, and thus not suitable for building houses, they can only be used to give offers to the god, who will pick them with the lighting.
You catch two birds with one stone:
- keep your people safe
- throw a god driven decision making process in your tribe