What's wrong with high humidity?

Condensation when the temperature drops.

Yep. Also a tendency to increase leakage in hydroscopic and hydrophilic components such as some film capacitors, phenolic circuit boards, paper insulators, paper speaker grills, some microphone elements, and some carbon comp resistors. I designed marine radios for too many years and water absorption was a serious consideration. We even designed most radios with vertically mounted boards to prevent condensation from puddling. In humid climates, there was the added bonus of mold and mildew. I've had to clean out radios that looked like a biology experiement gone wild.

I did QA on the PRC-77 manpack radio. One test was a pressure test under three feet of water, then you had to open the case and look for any signs of moisture.

Thanks.

Thanks also.