What Causes Condensation in Tents

Waking up and discovering that the inside walls of your tent are wet is a nuisance that torments everyone from backpackers at remote sites in the mountains to families spending a night away from home at nearby campgrounds. Wet walls are the result of condensation and once you understand what causes condensation in tents, you can take steps to reduce it in yours. 

• What Causes Condensation in Tents?
• Reducing Condensation in Tents
• Moisture Maintenance

What Causes Condensation in Tents? 

Condensation forms when warm, humid air contacts a cold surface; for example, consider how post-hike beers “sweat” when they go from an ice-cold cooler to the warm air outside. A similar process happens inside your tent when warm, moist air created by your breath, body, and gear inside encounters a rainfly cooled by colder air outside the tent—converting the gaseous water vapor to a liquid state and collecting on the inside walls of your tent. The greater the temperature disparity between the air inside and outside, the faster condensation occurs. 

Reducing Condensation in Tents

Since condensation is the result of the air inside and outside of your tent commingling, there are a handful of simple steps you can take to reduce it.  

Create Airflow: Moving warm air from the inside of a tent to the outside is the most effective way to reduce condensation. You can do this by:

• Staking the tent and fly taught to maximize airspace between them 
• Opening up vestibules 
• Opening any vents 
• Pitching your tent with the door facing into the wind (so long as it’s not gusting) 

Pitch Perfect: The air under trees is warmer than out in the open, making it an ideal place to pitch a tent. Similarly, seek higher ground, as it exposes you to crosswinds and cold air pools in low points. Also, avoid sites near streams, lakes, ponds, and other wet or marshy areas where humidity is higher. 

Minimize Moisture: While there isn’t much you can do about the moisture your body releases, you can eliminate other condensation contributors. For example, stash wet boots outside the tent and make sure to dry soggy clothes before calling it a night or store them in a stuff sack outside the tent. Other moisture-minimizing ideas include:

• Not cooking or boiling water inside your tent
• Drying your dog off before letting him/her sleep inside 

Drying out gear like sleeping bags, pads, and backpacks before bringing them in the tent.

Moisture Maintenance 

If, despite your best efforts, you still wake up with wet tent walls, you can give them a jumpstart on drying by wiping the rainfly down with a camp towel. If you have time, let the rain fly soak up some sun before breaking down camp. Lastly, always make sure your tent is dry before storing it at home—putting a tent away damp leads to mold and is a sure way to shorten its life.