How to keep your car windows free of condensation

Fog can obscure the view of your car’s windows and windshield in both hot and cold weather. Fogging on the outside of the glass usually occurs in warmer climates, when cool air from the air conditioner hits the hot windows of your car. Meanwhile, internal condensation occurs when warmer air from inside collides with frigid air from outside, such as when you turn on the heater on a winter morning. Either way, it’s not safe to drive around with fogged up windows. Impaired vision is the last thing you need when the entire city is covered in snow and ice.

There are a few DIY hacks that can help you keep your car windows fog-free. Placing a few packs of silica gel on the dashboard and under the seats can help absorb excess moisture and prevent condensation on the glass. If you don’t have silica gel, put a few handfuls of cat litter in a clean sock, tie the end, and use it to wipe the fog from the windshield. Believe it or not, the desiccants in cat litter mask the smell of cat poop just as well as absorbing water vapor.

If you don’t like cats (you animal), mixing a teaspoon or two of plain white vinegar with water in a spray bottle is a fantastic solution to condensation and haze. Shaving cream – our favorite mist solution – works the same way as vinegar. Apply shaving cream (stay away from the gel variety) onto the glass with a clean microfiber cloth and let it sit for two minutes. The final step is to wipe off the excess with a separate towel, and voila.

Without sounding like a bespectacled lab rat, the humidity of the air in your car is the culprit behind foggy windows in the winter. Since humidity is the measurement of water droplets, water vapor, or moisture in the air, keeping the inside dry will control humidity and reduce the chance of fog blocking your view. Ice or snow on the carpets and seats of your boots, clothes and umbrella will evaporate quickly enough, and guess where all that moisture goes?

It evaporates into the air and the temperature difference between the damp interior of your car and the colder outside air causes fog to form on the windows and windshield. Meanwhile, older vehicles with worn rubber seals are not as waterproof as they used to be, allowing rainwater or moisture to enter the cabin and cause fogging. On the other hand, newer vehicles have optimized seals and better insulation, but it also means they are prone to condensation. Why? The airtight seals make it harder for moist indoor air to escape outside, and the water droplets have no choice but to fog up the windows when the mercury drops.

It may sound counterintuitive in the dead of winter, but turning on the air conditioning can significantly reduce humidity and prevent condensation. Switching the climate control to “outdoor” or “fresh air” instead of “recirculating” will speed things up because it allows cooler outside air to enter the cabin, lowering humidity and removing condensation. If your car has a windshield defroster, turn it on and leave it on to demist the windshield and windows.

The quickest way to demist your car’s windshield in cold weather is to turn the heat up to maximum, turn on the air conditioning, switch from “recirculating” to “outside” and opening the windows (only if possible) to speed up dehumidification. There is science behind the technology, but thank goodness we are a car camp. Finally, keeping the windows and windshield clean inside and out will prevent condensation on the glass. Avoid using ammonia-based glass cleaners to prevent streaks.