A stagnant high pressure system with hot seawater underneath can lead to high dewpoints but low precipitation. Mediterranean Sea climates is a classic example, but a stuck Bermuda High over the Atlantic can result in something similar. One of the hottest month (and definitely most humid) long spells in recent decades here, but not much rainfall until the end when the airmass started to weaken. Here's 2013, you can see the dews were stuck at around 70°F with little variation:
more typical year [that spike in early September is an obvious error] has lower dewpoint averages and more variability:
July 2016 was even drier than 2013; also fairly hot, but dewpoints more normal [though still a bit above average] so low relative humidity. More typical drought conditions. Very wet summer weather here can often be with cooler than usual weather; more fronts and colder air influx. So a bit lower dews than usual, higher relative humidity.
So, depends on season & climate. I think overall it's correct, especially outside summer that wetter = more humid [but probably correlates a bit more with relative humidity than dewpoint].
source for plots
http://mesonet.agron.iastate.edu/plo...i=100&_fmt=png