One can think of the changes in the degrees of freedom of the molecules as a type of molecular energy, separate from the actual motion of the molecules, which we measure as temperature. So, the temperature can be constant (the molecular speed does not change), but the freedom of movement changes as water goes to vapor (evaporation) or back (condensation ), which means energy must be supplied or removed. This energy is called latent heat, because it is "hidden" away in the molecules without changing the temperature of the substance. The loss or gain of this energy, though, does affect the temperature of the substance's environment, because the respective gain or loss of this heat will raise or lower the temperature around the water substance. Evaporative cooling occurs, then, from the evaporating water absorbing energy from the environment (ex., water droplets evaporating from your skin cools the skin as latent heat is absorbed out of the skin by the water).