You are describing a bad battery. If you want to know what is draining it, remove the ground cable, insert an ammeter, and measure the current flow. Wait three minutes after connecting the meter to get an accurate measurement. You must see less than .06 amp (60milliamps), any higher value indicates a problem. You must wait 3 minutes, as currrent flow will be high at first, until modules hibernate.

It is possible you had water instrusion and your CLP/SSM is now wet and destroyed, draining the battery, but in a Coupe I really doubt that.
Also, it is possible water backed up in the windshield drain, flooded the blower for the climate control, and that resistor/regulator is flowing current - but again, after ONE night, I doubt this.

I suppose hitting the skunk could have caused damage under the car to the alternator, but I really can't see that happening.

In any event, you don't diagnose current flow by observing battery voltage, you do so by measuring the current. PLease see the attached, this comes up so often, I took the time to write a document addressing this very issue.