No, hot water does not weigh less than cold water. The weight of a substance is determined by its mass, and the mass of a given amount of water remains constant regardless of its temperature.
When water is heated, its temperature increases, but its mass does not change. However, the volume of water does change with temperature. Water expands as it is heated and contracts as it is cooled. This expansion and contraction are due to changes in its density.
At the same volume, hot water is less dense than cold water. This means that a given volume of hot water will weigh slightly less than the same volume of cold water. However, if you measure an equal amount of hot water and cold water by mass, the weights will be the same.
So, while the density and volume of water change with temperature, the mass and weight of water remain constant regardless of its temperature.