Wind-driven rain leaks

A home can stay dry through a dozen gentle rains and then leak in one storm. Wind pushes water sideways and even upward, testing joints that ordinary rain never reaches. On an exposed coastal lot, that happens more often.

Where it gets in

• Window and slider frames, especially at the sill and corners.
• Door thresholds facing the weather.
• Stucco cracks and joints where different materials meet.
• Vents and penetrations through walls.
• Deck-to-wall connections and balcony doors.
• Chimney and skylight flashing.

Clues

• Leaks only during storms from a certain direction.
• Water at the bottom corners of windows.
• Stains on the wall below a window, or bubbling paint.
• Wet carpet along an exterior wall.

During the storm

• Towels and a container at the leak; move belongings.
• Plastic and tape over the inside of the opening if reachable safely.
• Photograph it while it is happening; that evidence is hard to recreate.
• Do not climb ladders or go on roofs in wind and rain.

After the storm

1. Measure moisture in the wall below the leak; wall cavities can hold water you cannot see.
2. Dry the cavity if readings are high; sometimes baseboards or drywall come off.
3. Have a window, stucco or roofing contractor find and repair the entry point.
4. A water test with a hose can confirm the repair.

Wind direction and exposure

Storm winds can arrive from different directions, and the walls, windows and doors on the exposed side take most of the water. Homes on bluffs and ridgelines often see stronger wind than those tucked into canyons. Note which side of the house leaked and the wind direction during the storm; it narrows the search for the entry point.

How water climbs

Wind pressure on the outside of a wall pushes water through gaps that would stay dry in calm rain. It can drive water up and over a window sill, through weep holes in the wrong direction, and under thresholds. Windows and doors are designed with drainage paths for this; when those paths are blocked or flashing is missing, water goes inside the wall instead.

Hidden damage inside the wall

Water that gets past the window frame often runs down the framing inside the wall and shows up at the baseboard or in the subfloor, sometimes feet away from the window. Moisture readings along the wall below and to each side of the window, from the floor up, tell you how far it went. Wet insulation and bottom plates are common findings.

Repair strategy

1. Temporary protection during storms.
2. Drying the affected wall cavity and floor.
3. Investigation by a window, stucco or waterproofing specialist, often with controlled water testing.
4. Permanent repair: reflashing, resealing, sometimes replacing the window.
5. A water test before closing walls.

Insurance perspective

Policies often distinguish between rain that enters through an opening created by a storm, such as wind damage to a roof, and rain that leaks through an existing gap over time. Report promptly, document the storm and damage, and let the adjuster determine coverage.

Before the next storm

• Clear window tracks and weep slots.
• Check exterior caulk around frames and penetrations.
• Look for stucco cracks wider than a hairline near openings.
• Make sure deck drains flow.
• Keep plastic sheeting, painter's tape and towels on hand.

Recording a leak in progress

Video during the storm is the single most persuasive piece of evidence for both the repair contractor and the insurer. Show the outside conditions, then the leak point, then the spread. Say the date and time out loud in the video.

Mold watch after a storm

CDC and EPA both point to the same window: dry wet materials within 24 to 48 hours. Wind-driven rain often soaks the inside of a wall where you cannot see it. Within two days of a storm, check below windows and sliders for staining, soft drywall or a musty smell, and get a moisture reading if anything seems off.

Sources, accessed Oct 16 to 17, 2026: California Department of Insurance: Residential insurance guides · EPA: A brief guide to mold, moisture and your home · CDC: Mold, basic facts and prevention