No matter what the climate is like where you live, keeping the temperature comfortable inside your car often means battling foggy windows. If you live in a climate with cold winters, staying warm in your chilly car means turning on the heater — and battling the resultant fog on the inside of your windows. In warm, humid areas, turning on the AC can cause the opposite issue — fog blurring your windows from the outside.
The reason for foggy windows has to do with temperature and the air’s moisture content. On a cold day, any moisture in the air inside your car — from passengers exhaling, from snow on your boots, etc. — turns to condensation when it hits air next to the windows that’s below a certain temperature, called the dew point. The condensation is what makes your car’s windows appear foggy. On a hot, humid day, the opposite happens, when the muggy air outside your car reaches the dew point against your windshield after it’s cooled by your AC system.
Whether the fog is on the inside or the outside of your windows, any time you can’t see clearly in all directions, it’s dangerous. So, it’s important to know how to make sure your windows are clear — no matter the weather.
When you’re dealing with cold weather outside and you turn on the heater inside your car, the fog typically will start to form on the inside of your car windows. Here are some options to clear those windows up:
When the temperature and moisture level outside are greater than inside the car, moisture will condense on the exterior of the car glass. In this situation, the trick is to increase the temperature on the inside of the car to accumulate less moisture on the outside. Keep the following tips in mind:
Trying to see through fogged-up windows is a driving hazard, but with these tips, you can help increase your driving safety—no matter what the weather.