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Eliminating Tent Condensation (And What Causes It)

There are many challenges to overcome when camping. From the hike to your campsite, to the bugs and critters you must contend with when you arrive. However, condensation is one of the challenges every camper faces at some point, so it’s useful to know to how eliminate tent condensation.

You can eliminate tent condensation by choosing your location carefully, or by using a dehumidifier. Condensation forms when there is a large temperature difference between the inside and outside of the tent. This difference causes dew or water droplets to form, resulting in condensation.

Below, we’ll go into more detail about what causes tent condensation, and the different ways you can both prevent and eliminate tent condensation. We’ll also suggest some useful tools for eliminating condensation, but first let’s discuss what condensation is in more detail.

What Is Tent Condensation?

Condensation occurs when a liquid, in this case water, changes from a gaseous/vaporous state to a liquid state. This change happens when the warmer air vapor hits a cooler surface, like when you breathe warm humid air into the air in your tent. This air floats to the cooler surface of the tent at night and changes from vapor to liquid.

How Does Water Change From Vapor To Liquid?

Vapor molecules are fast-moving and carry energy. When the molecules go near or contact a cooler surface, they tend to slow down and collect in the form of dew. This newly formed water sits on your tent just waiting for you to rub your hand across or bump your head into the tent walls. 

Relative Humidity

When the temperature outside the tent gets low enough, water vapor needs to turn into a liquid. When you are sleeping or sitting in your tent you are breathing warm, moist air out, increasing the humidity of the air. As the temperatures outside your tent cool down at night, the moist air you breathe out collides with the cold tent surface, resulting in condensation.

What Causes Tent Condensation?

The Weather

Weather conditions play a role in tent condensation. Typically, you think of precipitation: rain and snow. These conditions will have similar effects on whether you get condensation.

First, the rain will cause an increase in humidity and a drop in temperature. If you are sitting in your tent, you will feel the tent getting stuffy inside. Condensation will occur when the temperature drops enough to cause a disparity between the inside and outside of the tent as noted previously.

Second, snowy conditions can drop the temperature outside, causing the temperature difference needed, but it won’t necessarily cause the inside of the tent to gain humidity.

Human Breath

We breathe out around 40 grams of water vapor per hour when laying down. If you are in your tent for seven hours, that is a total of 280 grams of water vapor (or 9.8 ounces). This additional vapor adds to the humidity and eventually leads to condensation.

Wet Clothes, Socks, And Boots

After a long day of hiking, your clothes and boots get soggy from perspiration, rain, fog, etc. So, placing them in your tent for the night adds to the humidity level. This will add to the condensation as the temperature drops outside and your clothes attempt to “evaporate” the moisture.

Dogs

Because dogs don’t perspire, they reduce their body heat through panting. A long day on the trail and you could have a panting dog next to you for much of the night. When a dog pants it expels the heat and causes moisture to evaporate thus cooling the tongue and reducing body heat slowly over time.

This additional moisture in the air adds to the humidity. Depending on the time of the year, most dogs can sleep outside of the tent – something that should be practiced before your trip. Nobody wants to hear a howling dog all night long!

Backpacks, Sleeping Bags And Pads

These items do not inherently carry moisture. However, if you do not dry your gear from the night before, bags, pads, and backpacks can bring water back into the tent after a long day. Also, if you get rained on during the day it is unlikely that your backpack is completely dry when you set up camp for the night.

So, with all of this in mind, how do you eliminate tent condensation?

How To Eliminate Tent Condensation

Diurnal Temperature Ranges

The diurnal temperature range (difference in the maximum and minimum temperatures in one day) varies by region and what are called diurnal zones. Where I live in New Hampshire, the average diurnal range during the summer is about 20 to 23 degrees. So, with a relatively low temperature range you might assume less condensation.

However, the increased humidity in the Northeast causes a good deal of condensation on your tent. Therefore, condensation is worse with large diurnal temperature ranges and higher humidity.

Also, the Northeast has such high humidity that the tent tends to get very ‘stuffy’ during a summer hike, lending to the ‘uncomfortableness’ of getting a good night’s sleep. So, find out what your diurnal temperature range is and your relative humidity in your area. This will help you plan for your next trip.

Tent Placement

Tent placement can make a huge difference when it comes to eliminating tent condensation. Rivers and streams have increased humidity surrounding them. So, it makes sense that setting up the tent near a river will increase condensation!

In Open Fields Verse Under Trees

If you set up your tent out in the open field, the temperature will drop further than if you set up under a tree or at the edge of the woods. Setting up your tent under a tree is advised to keep it warm throughout the night. But be aware of deadfalls and widow makers to limit the chance of a branch falling on your tent while you sleep!

Rainy Days

Rainy days will produce much greater humidity and water vapor leading to a higher level of condensation. So, aside from the main benefits of camping during dry weather, you can also limit your tent condensation by avoiding camping in the rain.

Ventilation

By maintaining good ventilation through your tent, you can increase the rate that water will evaporate, and allow for movement of the humid air out of your tent. This limits condensation. Setting up your tent facing the wind is a good way to provide ventilation in your tent and increase evaporative cooling.

Other Ways To Eliminate Tent Condensation

Here are some other ways to eliminate tent condensation:

  • Remove your backpack, and any wet clothes, socks, or boots
  • Properly ventilate your tent – If you do not have good ventilation it is probably a good idea to purchase a better tent
  • Do not cook or boil water in your tent, as this adds water vapor and therefore humidity into the air
  • Open windows and your rainfly to balance temperature and provide proper ventilation
  • Set up your tent facing into the wind
  • DO NOT light a candle inside your tent – While this seems like it would help reduce humidity and increase temperature, it also presents a fire risk
  • Don’t touch the tent walls
  • Dry the tent in the sun, even if that means taking it out midday while you are having lunch on the trail
  • Dry all the items by the fire or in the sun after a long hike
  • Remove and dry all sleeping items before putting them into a backpack for the day
  • Bring a ‘shammy’ with you to dry wet areas on your tent – These work great at eliminating really wet areas of the tent before packing up for the day
  • Use a small battery-operated fan to increase ventilation and circulate the air in the tent
  • Stake the tent taut – This allows the hydrostatic head properties to work effectively and reduce the chance of your tent leaking

Should You Use Tent Dehumidifiers?

You can use tent dehumidifiers to eliminate tent condensation. In recent years, tent dehumidifiers have gained popularity. As the name implies, they reduce the humidity in your tent. Reducing the humidity will reduce the chance of condensation when the temperature drops at night.

Chemical Dehumidifiers

Chemical dehumidifiers use non-toxic calcium chloride salts (desiccants) to draw water from the air. They work well in a small space like a tent but are not reusable. When hiking, place them inside the tent, hanging them from the tent supports.

Rechargeable Dehumidifiers

Rechargeable dehumidifiers like the VERITAS Small, Portable, Rechargeable, and Renewable Dehumidifier can remove up to 150 ml of water vapor per day. This should be enough to get through the night comfortably and help by eliminating tent condensation. This is good for short humid backpacking trips or car camping, as it only weighs 8.1 ounces.

Final Thoughts

Tent condensation occurs as the humid air inside the tent makes contact with the tent walls, which are cold as a result of cooler temperatures outside the tent. Eliminating tent condensation is all about reducing the humidity inside the tent, and keeping it well ventilated.