High levels of humidity, lack of proper ventilation, and temperature differentials between the interior and exterior of a sleeping bag can cause condensation on the of outside your sleeping bag. Below is some advice you may want to follow to prevent condensation: 1. Ventilate your tent: Try to fully open your vents or windows to allow air to circulate and prevent moisture from building inside the tent that will ultimately lead to condensation. 2. Choose a suitable campsite: Condensation will likely happen in areas with high humidity and low-lying regions. With that in mind, it is best to avoid camping in these locations when trying to prevent condensation. 3. Use a moisture barrier: Placing a footprint or a groundsheet under your tent is one effective way to block out moisture from the ground that may seep into the tent and cause condensation. 4. Wear appropriate clothing: Try to remove clothing layers when it gets too hot, as wearing some clothes can make you sweat more than you usually do. Wear the appropriate clothes so that moisture in the tent won’t increase and prevent condensation from potentially happening. 5. Use a sleeping bag liner: Sleeping bag liners that are made out of breathable materials help to wick away moisture from your body and keep the sleeping bag dry as it prevents the process of condensation. 6. Dry out your sleeping bag: When condensation starts appearing on the exterior of your sleeping bag, immediately dry it out on a well-ventilated area, and you may also use a clean cloth to get rid of the moisture. Try to follow these tips to make your sleeping experience at night comfortable and free from condensation.