If you've got a leaking glass seal your first step is to move your car under cover. To be 100% sure it's your glass seal leaking check for other possible causes of leaks first. These could be;
• cracks in the windscreen or window. If you find a crack you may need a windscreen repair or replacement
• water around or coming out of air conditioning vents
• holes in the car body
• damage in the door seal
• water coming from the sunroof.
Once you can rule out any other source of leaking, it's time to check on your window seals.