The temperate zones have the coolest climates on earth are relatively dry generally have a climate warmer than the tropics are the zones closest to the equator are relatively wet

I would say that the temperate zones though they do have areas such as the Pacific NW that have significant rainfall, but relative to the tropics are apparently relatively dry since they contain most of the world's deserts like the Sahara, the Sonora and the Gobi and the Atacama for example.

That would be a working theory.