That is because the dew point is a measure of how much water vapor is in the air and relative humidity is a measure of how much water vapor is in the air relative to how much water vapor could be in ...
Summer is here, and heat and humidity have arrived.
Relative humidity measures how much moisture is in the air compared to how much it could hold at a given temperature. It is simply the dew point temperature divided by the air temperature, times 100.
The heat index shows how humidity makes hot days feel hotter, and why direct sun can push dangerous conditions even higher.