Sometimes the weather is so hot that you can't take as much fluid as you lose by sweating, even though the heat produced by the muscles must be treated somehow and the hydrated state of the body should be maintained as well to reach your personal top performance. In this kind of weather conditions, Enduraid sends you a warning message to cool yourself in any other way (sponge, icebag, hat etc.) to save some sweat! See the first 18 seconds of the video!
https://www.youtube.com/watch?v=2yiSSVlyDPo&t=67s Patrick Lange, the later winner, takes 6 sponges out of his jersey, but he actually had two more at the neck that he had already thrown out. These were ice-soaked sponges that were constantly exchanged because he knew that in that Kona weather (high temperature and humidity), he could not consume enough fluids that he would have lost via sweating, without cooling.