In my experience, doing 3-6 reps is the sweet spot for this type of training. As this is done in a circuit fashion with incomplete rest, you'll be unable to perform the same loads as during traditional lifting sessions.
The water on your body changes to a gas called water vapor. Water turns into a gas through a process called evaporation. Heat makes water evaporate faster. All air has some water vapor. Tropical rain forests and deserts are both hot.
The drier it is, the more water will evaporate from the kettle, causing cooling due to evaporation, which means two things...1) your water will cool faster, and 2) since some of the water evaporates, you now have less water in your kettle, so your water will cool faster.