Water showing up inside your car during the rainy season rarely comes from a leaking window. It usually means a drain somewhere is clogged, and the fix is almost always simpler than people think.
If water shows up inside your car during South Florida's rainy season, the instinct is to blame a window seal or a bad weatherstrip. Most of the time that is not what is happening. The far more common cause is a clogged drain, and the fix is usually simpler and cheaper than people expect once they know where to look. Where the Water Is Actually Coming From Cars have several drainage paths built in specifically to move rainwater away from the cabin. When one of these gets blocked, water that is supposed to run harmlessly onto the ground instead backs up and finds a way inside. Sunroof drain tubes. Most sunroofs have four small drain channels, one at each corner of the opening, that carry water down through the A-pillars and C-pillars and out near the front fenders or rear wheel wells. These tubes are narrow and easy to clog. Cowl drains. The cowl is the panel at the base of the windshield, under the wiper arms. It has drain holes that let rain run off instead of pooling against the windshield seal or flowing into the HVAC intake. Door drain channels. The bottom of every door has small weep holes that let water that gets past the window seal run back out instead of collecting inside the door skin. Trunk and taillight seals. Taillight housings are often sealed with rubber grommets that can crack or shrink, letting water track along the trunk's inner panels. Any of these can clog with debris, and once they do, a normal rain event behaves like a leak even though nothing about the seal itself has failed. Why South Florida's Rainy Season Makes This Worse A few things about this region line up to make clogged drains more common here than almost anywhere else. Oak and pine pollen loads are heavy in spring, right before the wet season starts. Lovebug season in late spring and again in late summer leaves a layer of insect residue on cowls and grilles that mixes with pollen and dust into a paste that hardens when it dries between storms. Add in palm debris and leaf litter, and the cowl area in particular accumulates material fast. Then the rain itself does the rest. South Florida's wet season is defined by intense, short-duration afternoon downpours almost every day for months. A drain that is half-blocked might handle a light rain fine and then overflow completely during a fifteen-minute deluge. Because the humidity rarely lets anything dry out completely between storms, any water that does get trapped sits there longer than it would in a drier climate, which is exactly the condition mold needs to take hold. How to Check Your Drains Before It Becomes a Problem None of this requires special tools, and checking is worth doing before the heaviest part of the season arrives. For a sunroof, open it partway and look along the track for leaves or grit sitting in the corners. A simple test is to pour a small amount of water slowly into one corner of the open track and watch for it to drip out near the base of the corresponding pillar a few seconds later. If nothing comes out, that drain is blocked. For the cowl, the panel usually has to be removed or partially lifted to see the actual drain holes, which is more involved on some vehicles than others. At minimum, clear visible leaf litter and debris from the exposed cowl area at the base of the windshield with a soft brush or low-pressure air, never a metal tool or anything that