High humidity trapped inside the car does this. Happened for me too.
You are bringing in the moisture on your feet in this weather, no matter how much you kick off the snow. It stays in your floor mats and carpet which never really have a full chance to dry.
Untill the weather gets better ;
- Don’t park with the heater system in any of the recirculating modes.
- Get some good ol’ school chalk sticks and place them in various areas in the cabin like door pockets and under the seat. They are a good absorbant.
- Given enough time before parking, Open a window a tad and turn the heater on high to expel some humidity.
- If the weather’s ok, take out your mats to bask in the sunlight to dry.
I did these thing to my 06 Escape hybrid when it frosted up the winters of 06 & 07.
It has not ever happened since. The school chalk is still in the door pockets and under the seats.
“Hey, look what I found, Uncle.”
“Just leave it there, it’s a long story.”