When I get into my car after there has been a heavy rain the driver's side floor mat is wet. I poked my head under the dash (above where your left shin would be) and found a drop of water hanging off. I then felt around under the dash a bunch of water poored down onto the mat.

Does anyone know where the water could be coming from? There is no water on the top of the dash or on the inside of the door or anywhere else. Also, there is no leak after a light rain or after washing my car, but only after a heavy rain.

I'm thinking that the water may be coming in from under the cowl (black plastic piece that sits around the wipers and across the bottom of the windshield), however, I the wipers are very stubborn to get off as of now.

 

do you have a sunroof ?

 

No sunroof. I read that it could also be the AC condensation, however, I use the AC almost every day and I only get a wet floor mat after a heavy rain.

If the leak is from under the cowl, is there a recommended way of getting the wipers off? I pulled on them pretty good but they won't budge (yes, I took off the nut :P)

 

it can be a leak around the windsheild or under the cowl.
I'd try running the hose on the cowl area and watch for water , no water then move up the windsheild. trying to find the leak

Wipers are aluminum and shafts are steel try soaking where the nut was in penetrating oil
Then reinstall the nut loosely , use a two armed gear puller to grab the sides and pull up on it to break it loose