Sleep dry: pick a slope, not a hollow
You want a campsite that catches a breeze and is not in a low spot.
Dew forms when warm, moist air meets a cold surface—like your tent fly. Cold air sinks, so valleys and depressions collect both cold air and moisture. If you pitch in a hollow, you’re basically camping in a dew bathtub. Same goes for right next to a lake or river. That’s where the humidity lives.
What you want is a slight rise, open enough to get some airflow but not so exposed that wind becomes a problem. A gentle slope lets cold air drain away. A bit of overhead tree cover can help block radiational cooling (which makes dew worse), but thick canopy can also trap moisture. The sweet spot is a semi-open spot on higher ground with some wind exposure.
If you have to choose between a dense forest floor and a breezy ridge, take the ridge. You’ll trade a little wind for a lot less wet gear.
A little evening breeze is your friend. A valley is not.
