Its negligible but yeah. In the middle of the afternoon with good mixing, especially if comparing a forested hill to a field in a valley.
Here's a sounding this afternoon from the CT Valley. The dew point increases about a degree or so with height.
But the temperature difference is crazy. Look at that extremely long tail on the temperature plot... that is an insane lapse rate in the lowest 1,000ft. There's a reason DIT talks dews and not temperatures in the hills of NE CT. The temps cool off a lot with any height outside the CT Valley.