Intermittent ignition switch failure

This is a question that is really more about the curiosity of this issue. I both wonder what it is but also if others have seen it.
When the ambient temp and humidity are just right there is a 50/50 chance that my car will not turn over.
I can just about call it, when it's going to happen. Unfortunatly it is the worst type of electrical problem in that it is not consistent. It has done it for a few years now. I first wrongly suspected the relay and replaced it. Then I decided it must be...

Intermittent ignition switch failure