How do I stop my car windows from fogging?

To stop car windows from fogging, focus on reducing moisture in the cabin and matching the glass temperature to the air around it.

Quickly clear fog now

If the fog is on the inside (common in cold weather):

1. Turn on the defroster/defogger.
2. Use warm air and A/C together if possible. The A/C helps dry the air, and the heat helps clear the glass faster.
3. Turn off recirculation. Fresh outside air is usually drier than the humid air trapped inside the cabin.
4. Crack a window slightly if needed to let humid air escape.

If the fog is on the outside (common in warm, humid weather):

1. Use the windshield wipers to clear it.
2. Adjust the cabin temperature so the windshield is less cold relative to the outside air.
3. Avoid overusing recirculation if it makes the temperature difference worse.

Prevent fogging

• Keep the inside glass clean.
• Use the defroster early before the glass gets heavily fogged.
• Reduce cabin moisture: dry wet floor mats, remove snow or water from shoes and clothes, and fix leaks if you notice them.
• Consider an anti-fog product made for car glass.

If your windows keep fogging even with the defroster on, check the cabin air filter and look for damp carpets, standing water, or a possible heater-core leak.

If fogging is persistent, it can help to have the HVAC system inspected, especially if there’s a musty smell, visible moisture, or poor airflow.