Can Heavy Rain Damage Car Paint?

[DiCole]

Yes, it can corrode the car paint. Rainwater is weakly acidic, and due to environmental pollution, it may appear clean on the surface but should not be ignored. If your car is left wet from rain for a long time without being washed, the concentration of acidic substances in localized areas will increase. As we all know, acidic substances can corrode car paint. Here are some relevant details: Post-rain care: After rain, water spots on the car body will gradually shrink, increasing the concentration of acidic substances in the rainwater. If these spots are not rinsed off with clean water promptly, they will eventually damage the paint over time. Undercarriage maintenance: Rainwater and moisture can seep into the car body through small holes in the undercarriage, leading to rust and peeling, which is often hard to notice. Therefore, after heavy rain, it's essential to perform some undercarriage maintenance.

[VanFelix]

I just washed my car two days ago, and after a heavy rain, it was covered in dusty water marks. What really damages the car paint is the dust and dirt carried by the rainwater. When the water flows over the body, these particles create fine swirl marks. It's even worse if parked under a tree—rainwater mixed with tree sap and bird droppings forms sticky grime on the paint, which, when baked by the sun, etches directly into the clear coat. Our auto repair shop often receives cars with dull paint after rain, and we have to use hard water stain removers to clean them. It's recommended to rinse the car with running water as soon as possible after heavy rain and avoid scrubbing with a dry cloth.

[JustinRose]

Our family has been running a car wash for ten years, and there's always a rush for polishing after heavy rain. The acidic substances in rainwater can slowly corrode the car paint, especially causing yellow spots on white cars. But even more damaging is not washing the car after the rain, waiting for the sun to dry the water droplets, leaving white marks from calcium and magnesium ions on the paint. Last time, a Porsche was left in an open parking lot for three days in the rain, and the water stains on the hood took half an hour of scrubbing with clay bar to remove. Remember, washing the car within 48 hours after the rain is most effective.

[DeChristian]

High school chemistry teachers mentioned that rainwater with a pH around 5.6 is considered acid rain, which actually causes limited damage to car paint. The real trouble comes with heavy rain near industrial areas, which may contain sulfides or nitrogen oxides. Once, my car got drenched in a downpour near a chemical plant, and the next day, I noticed etched-like spots on the hood. The 4S store explained that this was the result of acid rain combined with UV rays, causing localized carbonization of the clear coat and forming pits. Now, whenever I see dark clouds, I immediately park my car in the garage. For outdoor parking exceeding three months, it's recommended to apply a ceramic coating.