Invisible water is vapor (gaseous form), and high ‘humidity’ (% of water vapor in air) can make you feel hotter or cooler.

My Waste Management bill had this advice to keep cool: ‘Hang a wet sheet by a window and the temperature will cool by evaporation.’
What they don’t see is the water vapor will just stay in the room, increasing humidity and intensifying the discomfort of hot temperatures.
Sometimes when hot, I get my scalp or arms wet to evaporate, but not a whole sheet.

Check the temperatures of your electronics & chargers, even if off. I exchanged the burning-up cable box with Time Warner, and the new one is just as hot when off; so I’ve been turning off the power strip every time even though it takes longer to reset. I’m thinking of buying a large baking cooling rack to let the air vent, but hot electronics can still heat up rooms over the hours.

Americans have widespread misunderstandings about vapor/humidity vs. mist/clouds/condensation, water in the gaseous vs. liquid states of matter. Everyone gets ice. I remember before the Beijing Olympics, national network medical editor Dr. N.S. was asked to assess the thick smoggy haze to see if it would be harmful for athletes; and she concluded, “It’s the humidity.” It was not: if you can see it, it’s condensation, liquid droplets. “I guess even doctors forget the water cycle.”

water cycle -tjstudentgalleryCalifornia Kindergarten Physical Sciences Content Standards 1b, 1c:

“1. Properties of materials can be observed, measured, and predicted. As a basis for
understanding this concept:…
b. Students know water can be a liquid or a solid and can be made to change back and forth from one form to the other.
c. Students know water left in an open container evaporates (goes into the air) but water in a closed container does not.”

http://www.cde.ca.gov/be/st/ss/documents/sciencestnd.pdf