THE SHORT ANSWER
Move furniture and electronics away from the wet area, catch drips, and note exactly where the water first appears. Do not touch a wet outlet, switch, light, cord, or appliance. Keep back and call a qualified electrician if water has reached electrical equipment. A leak visible at the window does not prove that the window itself is the entry point; rain can travel through the window opening or wall before it becomes visible indoors.
Before you try anything
Stay away from wet electrical equipment, bulging ceilings or walls, soft flooring, loose trim, cracked glass, and rapidly increasing water. Do not operate a breaker while standing in a wet area. Do not climb a ladder, go onto a roof, open a wall, remove trim, or take apart the window. Wait until rain, wind, and the ground outside are safe before making any exterior observation from ground level.
Before you begin
Use this guide for liquid water that appears at an accessible window during or shortly after rain. It covers observations you can make indoors or from the ground after the storm. It does not diagnose hidden flashing, wall, roof, mold, structural, or electrical damage. If the moisture forms evenly on the room-side glass without a rain pattern, start with the separate condensation guide instead.
Use absorbent towels, a bucket or tray, a flashlight, a phone or camera, and a note for the time, weather, and wind direction. Have the window brand, model, product label, and official care instructions available if you can identify them without removing parts. You do not need a ladder, pry tool, caulk gun, electrical tester, or garden hose for this check.
In a rental, report the problem to your landlord or property manager before making repairs. Building rules and local requirements vary.
Work through the checks
- 01
Protect the room first
Move furniture, rugs, curtains, and electronics away from the wet area when you can do so without approaching wet electrical equipment or unstable materials. Catch drips and blot accessible clean water. Take photos before moving damaged items if it is safe; renters should also notify property maintenance.
- 02
Confirm that the moisture follows rain
Record when the rain began and when the water appeared. Note whether the glass is simply fogged on the room side, whether water is entering at a distinct edge, and whether the area also becomes wet when it is not raining. Rain-linked liquid water needs a different evaluation from ordinary indoor condensation.
- 03
Mark the first visible water
Watch from a safe indoor position and record the first wet point: above the window, at a top corner, along a side, between the sash and frame, in the bottom track, at the sill, or on the wall below. Water can travel inside an assembly, so this point is evidence for an inspector rather than proof of the outdoor entry point.
- 04
Record the storm pattern
Note rain intensity, wind direction, how long the rain had been falling, and which windows were affected. A leak that appears only with wind from one direction or at several windows on the same wall may help a professional decide where to inspect, but it does not identify a single cause by itself.
- 05
Check the window from indoors
Confirm that the sash is fully closed and locked, because some windows are tested for performance in that position. Look for a displaced visible gasket, debris in an accessible track, or a product label. Do not drill, probe, remove hardware, or seal an opening. If the manufacturer documents a drainage system for your exact product, follow only its model-specific care instructions.
- 06
Look outside only when conditions are safe
After the storm, observe from the ground. Photograph visible staining, peeling paint, damaged trim, blocked gutters above the area, wall cracks, or a water path from higher on the wall. Do not climb for a closer view. Hidden flashing usually cannot be evaluated without removing materials, which belongs to an appropriate contractor.
- 07
Dry what you can reach and preserve the record
Dry accessible water-damaged areas and items as quickly as practical. EPA recommends drying wet areas and items within 24 to 48 hours to help prevent mold growth. Keep dated photos and notes, and continue watching for odor, discoloration, swelling, softness, or damp carpet after the visible surface looks dry.
- 08
Call the trade that matches the evidence
Start with the installer, manufacturer service provider, or a window specialist when the unit or its operation appears involved. Contact a siding or building-envelope contractor when stains begin above the window or affect several openings on one wall, and a roofer when the path appears to begin at the roof or roof-wall junction. Use a water-damage professional for wet hidden materials and a qualified electrician for any electrical exposure.
What your result means
These observations help choose a next step. They do not confirm a diagnosis.
| What you notice | What it tells you | Next step |
|---|---|---|
| Water first appears above the window or at an upper corner | The visible point may be receiving water from the head of the opening, the wall above, or another higher route. | Photograph the larger wall area and arrange a building-envelope, siding, roofing, or window-opening inspection as the site conditions suggest. |
| Water appears between the sash and frame | Closure, weather seals, hardware adjustment, or the unit itself may need model-specific inspection. | Confirm the window is closed and locked, record the product label, and contact the manufacturer, installer, or a window service professional. |
| Water briefly collects in the bottom track and drains outside | Some window products are designed to collect and drain limited water through an exterior drainage system. | Check the manual for the exact product. Do not block drainage openings, and seek service if water crosses into the room or the pooling persists. |
| Water remains in the track on a product with documented weep holes | Visible dirt or debris may be interfering with that product's intended drainage, or the condition may need service. | Follow the manufacturer's care instructions for that model. Do not enlarge, probe, or caulk the openings. |
| Several windows on one wall leak only in wind-driven rain | A shared exposure, wall detail, drainage path, or installation condition may be involved. | Record the wind direction and affected openings, then have the wall and window openings evaluated rather than sealing each indoor wet spot. |
| The area is damp without rain or the glass is uniformly wet on the room side | Indoor condensation, plumbing, or another moisture source may fit better than rain entry. | Use the condensation guide or arrange an inspection based on where the moisture appears; do not force the rain-leak explanation. |
| You find odor, bubbling paint, soft wood, damp carpet, or recurring stains | Moisture may extend behind finishes or have remained long enough to damage materials. | Stop surface-only fixes and arrange professional assessment of the moisture source and affected materials. |
Know what happens next
Check the outcome
Do not treat one dry storm or a clean-looking surface as proof of repair. Verification means the responsible professional has identified and corrected the water path, affected materials have dried, and comparable rain no longer produces new dampness, staining, swelling, odor, or pooling. Follow the window manufacturer's or contractor's documented check rather than improvising a high-pressure hose test.
When to call a professional
Stop DIY observation when water reaches electrical equipment, the ceiling or wall bulges, materials feel unstable or soft, water is increasing quickly, or inspection would require a ladder, roof access, dismantling, or opening the wall. Call for help when the leak repeats, wet materials cannot be dried promptly, visible mold or a persistent musty odor develops, or damage appears to extend beyond the accessible surface.
Take useful notes with you
A short record makes it easier to explain the problem to a landlord, technician, or responder. Do not collect notes during an emergency.
Notes stay in this page until you leave or reload. Download a copy to keep them. They are not sent to us.
Common questions
Why does the window leak only during wind-driven rain?
Wind can change how rain reaches joints and openings, but that pattern alone does not identify the failed part. Record the wind direction, affected windows, and first visible water point so an inspector can compare the unit, opening, wall, and higher water paths.
Is water in the bottom track always a failed window?
No. Some products have drainage systems that can temporarily hold and then discharge water. Check the instructions for your exact window. Water entering the room, persistent pooling, or repeated overflow still needs attention.
Should I caulk the weep holes?
No. Drainage openings are intended to let water leave products that use them. Do not seal, enlarge, or probe an opening. Identify the window and follow its official maintenance instructions.
Can I find the leak with a garden hose?
An uncontrolled hose test can add water to the wall and may not reproduce real wind-driven rain. Leave diagnostic water testing to a qualified person who can control the sequence, pressure, location, and interior observation.
Who should I call first?
Call the installer, manufacturer service provider, or a window specialist when the unit or its operation is the main clue. Staining above several windows may point toward a siding or building-envelope inspection, while a path beginning near the roof may call for a roofer. Use an electrician whenever electrical equipment became wet.
How quickly should wet materials be dried?
EPA recommends drying water-damaged areas and items within 24 to 48 hours to help prevent mold growth. Materials that stay damp, smell musty, soften, swell, or cannot be reached may require professional drying or removal.
How can I tell rain leakage from condensation?
Rain leakage follows a storm pattern and often starts at a particular edge, joint, or surrounding wall area. Room-side condensation typically forms on a cold interior surface and can follow indoor humidity rather than rain. Both can occur, so record the timing and exact surface instead of guessing.
Sources & scope
This is a desk-researched guide, not a hands-on test or an on-site diagnosis. A licensed tradesperson has not independently reviewed this edition. Follow your product’s manual and local requirements.
- Building America Solution Center: Look for Missing Window and Door Flashing
Supports treating window openings as part of the wall drainage system, observing visible moisture clues, preserving weep holes, and recognizing that hidden flashing cannot usually be confirmed without removing materials.
- U.S. EPA: How do I get rid of mold?
Supports fixing the moisture source and drying water-damaged areas and items within 24 to 48 hours to help prevent mold growth.
- Andersen Windows & Doors: Important Product, Care and Maintenance Information
Supports model-limited statements about drainage systems, exterior weep holes, temporary sill pooling, checking for visible debris, and keeping units closed and locked for tested performance.
- Electrical Safety Foundation International: Flooding and Disaster Safety
Supports staying away from water-exposed electrical equipment and having qualified professionals inspect it before it returns to service.
Published 2026-09-25 · Our editorial policy · Report a correction