How can I reduce condensation inside my tent?

A: Tent condensation is an eternal bugbear, a simple, unavoidable fact of physics: Tent occupants exhale warm, moist air. When this air hits a cool surface—i.e., the tent fly—any moisture condenses, leaving water on the fabric surface. Tents are actually designed to allow for this. The idea is that the moist air filters easily through the tent's non-waterproof inner canopy (although in many conditions, even very airy ripstop causes condensation), condenses on the rainfly, then flows down and drips harmlessly to the ground.

Ventilation is the key, as you want to get that moist air out of there as quickly as possible. So leave as many vents and doors open as you can—especially those high on the tent—and try to point the tent so prevailing breezes can blow through it. Of course, the tradeoff is whether you'll be comfortable temperature-wise. On a cold, windy day or night, though, condensation isn't really an issue, so button things up.

I find the problem to be worst on very still, cool nights, when the temps are around 35 to 40 degrees and the air is dry. Fall camping, in particular, seems to lend itself to condensation issues. Of course, the more people you have in a tent, the more apt you are to have condensation.

That said, most tents I've used in recent years deal with the problem fairly well. Some makers are even making tents with a single, non-breathable wall, in theory a sure formula for condensation. But good ventilation design mitigates the problem remarkably well. It's often helpful to leave your tent out in the morning sun to dry, but that's just the nature of the beast. Condensation is often, plainly and simply, unavoidable.