2002 Mazda 626 water leak in driver's side floor

I have noticed water pooling on the driver's side floor of our Mazda recently. It only seems to get wet when it rains and for the most part only while I'm driving in the rain. I've also noticed that the moisture is coming up through the carpet in the floor as the carpet under the floor mat will be wet but the top of the floor mat will be dry.

The trouble spot seems to be centered in the middle of the driver's side floor. Each time the floor has been wet the carpet along the sides and above and below have been dry. Only the middle of the floor board gets wet.

I thought the moisture may be coming from the AC but I have run the AC quite a bit on dry days and had no problems with water on those days.

Do you have any ideas what may be causing this or where the water is getting in? Has anyone else had this problem before either?

Any help would be appreciated.