That's exactly what it is.
Further, the more porous your hair is the more that humectant use in the appropriate dew points will be relevant to your hair. Ultimately just try to keep your hair as moisturized as possible and monitor how your hair reacts to different ingredients in different dews. You'll then figure out how much concern you need to have re. dews and humectants. Everyone's hair is different, but paying attention to dew points can help choose the right products/ingredients if you find your hair is more sensitive.
4a/3c, fine strands, low porosity, medium density
Last relaxer: Jan 2010 - BC'd: 2/27/11