Can You Turn on the Heater in a Car on Rainy Days?
3 Answers
On rainy days, it is more appropriate to use the cold air setting because the outside temperature is lower, and the interior temperature is higher than the outside, causing water vapor inside the car to condense on the windows. The reason for window fogging is the temperature difference and humidity, as water vapor condenses into mist when it meets cold surfaces. Air Convection Method: Lower the windows on both sides to allow air circulation inside the car, balancing the interior and exterior temperatures. Disadvantage: This method only works in light drizzles; in heavy rain, the car will get wet quickly. Cold Air Defogging Method: This involves turning on the air conditioning to quickly lower the interior temperature, which is suitable for emergency defogging while driving. Disadvantage: Since it's already cold on rainy days, using cold air for defogging might cause the front passengers to catch a cold if they are not dressed warmly.
Using the heater on rainy days is completely fine, and it's actually a good habit for car usage. I used to commute by car frequently, and on rainy days, the interior would be cold and damp. Turning on the heater instantly warms things up, and it utilizes the residual heat from the engine to warm the air, so it barely consumes extra fuel or electricity. The biggest benefit is how quickly it defogs the windows—heavy rain often causes fogging that obstructs visibility, but turning the heater on the windshield clears it up in just two minutes, significantly improving safety. It's recommended to start the car and wait a few minutes before turning on the heater, adjusting the temperature to a moderate level to avoid discomfort from excessive heat. Also, remember to regularly check the cabin air filter to ensure it's not clogged, maintaining good air quality. During routine maintenance, I also ask the technician to inspect the heating system—it doesn’t cost much but ensures a comfortable drive.
As a parent, I always turn on the heater when driving on rainy days. It keeps the kids in the back seat from catching a cold, and they sleep soundly when the car temperature stabilizes. Operating the heater is simple—just press the fan button and increase the temperature after starting the car. There's no need to turn on the AC switch, so it doesn’t increase fuel consumption at all. High humidity on rainy days can easily cause fogging on the windows, but the heater clears it up quickly, making long drives much safer. I also like using this weather to teach beginners, such as not setting the temperature too high to avoid affecting safe driving and using the recirculation mode to circulate warm air faster. Overall, this not only keeps everyone warm but also enhances safety—a handy trick for rainy-day driving.
