Is hot water heavier than the same volume of cold water?

Basically, it isn't. Cold water is denser than hot water. Therefore, it is cold water that is heavier than hot water (for equal volumes of water). Hot water is lighter than the same volume of cold water, not heavier. read more

Assuming the same volume hot water will be lighter than cold water. Because when water is hot the intermolecular space between the water molecules increases making them less dense. This is the reason hot liquid stays above cold liquid in a mixture. read more

Therefore, it is cold water that is heavier than hot water (for equal volumes of water). Hot water is lighter than the same volume of cold water, not heavier. The reason for the decrease in density as the temperature increases is that the water molecules cannot get so close together at higher temperatures. read more