For all the uses of relative humidity, dewpoint may be the better, quicker way to assess the comfort factor of the air. Dewpoint is a more direct measure of how much moisture is in the air.

PITTSBURGH (KDKA) -- It may be controversial to say in these parts, but it is ridiculous to use relative humidity as an indicator of comfort. While many people are familiar with relative humidity ...

This holds well for moist air, that is, as long as the relative humidity is above about 50%. Putting this to use, it's easy to figure out the dew point, and thus the expected comfort level ...