A few times this summer I've gotten in my car in the morning and turned the key to find nothing happening. The dash lights, etc. come on, but no spark/ignition. I might try it a couple of times before it suddenly starts as normal. I can't tell whether I'm doing anything to make it start (maybe I've taken out the key and re-inserted it).

This has only happened a handful of times, on tropically hot mornings as I recall. Maybe there's some condensation affecting some element in the ignition system? I want to figure it out before it leaves me stranded. Recently replaced cap and rotor and plugs with Volvo parts, by the way.