It's a question I get asked every spring, summer and fall - 'Why do you always show the dew point temperature? I want to know what the relative humidity is.'
Relative humidity, on the other hand, represents how close the air is to saturation and can change drastically from morning to afternoon. Dew point is more constant throughout the day. The relative humidity will be highest in the morning when the air temperature falls near the dew point temperature. But as the air heats up and the temperature rises, the relative humidity will decrease because there is a larger difference between the dew point and air temperature.
The dew point temperature tonight won't drop much past the mid 60's - which will actually keep our overnight lows in the low 70's. Moisture 'pooling' near a stationary boundary Tuesday could cause the dew point temperature in a few locations to reach 70 degrees for a time during the afternoon.