Why is there condensation inside my car windows in the morning?
Reviewed by the Skyview Auto Glass technical team — NWRD-, ASE- and DINITROL-trained technicians · Updated November 2026
Quick answer
Condensation forms when warm, moist air inside the cabin meets cold glass overnight. Wet mats, a leak past a windshield seal, or blocked drain tubes all raise the moisture. Dry the cabin, clear the drains, and run the air conditioning on fresh air to bring the humidity down.
Where the moisture comes from
Condensation appears when warm, damp air inside the car meets glass that has cooled overnight. The water vapor turns to liquid on the cold surface. The source is moisture trapped in the cabin — wet floor mats, damp seats, a leak past a windshield seal, or drain tubes blocked with leaves.
A leak past a windshield seal is one cause worth checking. See our leaking windshield repair page if the carpet near the base of the glass stays damp after rain.
How to get rid of condensation inside car windows
- Run the air conditioning on fresh air to dry the cabin, even in cool weather.
- Lift wet floor mats and dry them out of the car.
- Clear blocked drain tubes so water does not back up into the cabin.
- Leave a window cracked a few millimeters on dry days to vent moist air.
- Check for a windshield or door seal leak if the carpet stays wet after rain.
Stop the fog from coming back
Once the glass is clear, keep the cabin dry. Remove damp gear, dry the mats fully, and run the air conditioning on fresh air for the first few minutes of a drive. See our guide on stopping car windows from fogging up for the full routine.
Where hidden moisture hides
The cabin holds moisture in places you do not see. A damp headliner, wet foam under the carpet, and waterlogged door panels all release vapor into the air overnight, and that vapor settles on the cold glass. Even after you dry the visible mats, the hidden dampness keeps feeding condensation until the cabin is aired out.
Blocked drain tubes are a common culprit. The cowl drains at the base of the windshield and the sunroof drains in the roof pillars can clog with leaves and grit, and the water backs up into the cabin instead of running out. Clearing them often fixes a condensation problem that no amount of wiping the glass will solve.
A wet carpet near the base of the glass points to a seal leak rather than a blocked drain, and that is a different repair. If drying the cabin and clearing the drains does not stop the condensation, have the windshield seal checked before the moisture reaches the wiring under the carpet.
More questions about condensation inside car windows
Why are my car windows wet inside in the morning?
Warm, moist air in the cabin met cold glass overnight and condensed. Wet mats, a leak past a windshield seal, or blocked drains raise the moisture. Dry the cabin and clear the drains to stop it.
How do you remove mist from a windscreen?
Run the defroster with the air conditioning on and fresh air selected. The air conditioning dries the air, and warm dry air clears the glass in a minute or two. Wiping the glass only moves the moisture around.
Can a windshield leak cause condensation?
Yes. A leak past the windshield seal lets water into the cabin, which raises the humidity and shows up as condensation. If the carpet near the base of the glass stays damp, have the seal checked.
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