vents are prone to this, it comes in above the hood and runs down through the duct system and drips under the dash. You can watch it drip in a bad storm.
Aside from that, make sure your drain plugs are in. If they are out, water from the hi-way will spray up through them and you'll find you and your passenger standing in a puddle from nowhere!
This helps the cowl vent leak... Around $15-$20 bucks. There is a way to unclog them to drain better as well. But, Im also hoping to simply keep it all out. Helps keep the whole vent system dry.