September 15 Storm and Heavy-Rain Outlook: A 48-Hour Chicagoland Exterior Prep Plan

By Supreme Building Group | September 13, 2026 | Forecast preparation update

Chicagoland has a useful preparation window before the next period of unsettled weather. The National Weather Service Chicago says shower and thunderstorm chances increase late Monday night, with a stronger concern Tuesday and additional thunderstorm and flooding risks Wednesday and Thursday.

This is a forecast—not confirmation that a storm has damaged any community or property. Today’s official guidance does not support a new hail-damage claim. The practical reason to pay attention is the combination of possible strong storms, torrential downpours, and uncertainty about where a front may stall later in the week.

What the September 13 forecast says

The NWS Chicago Hazardous Weather Outlook lists no local thunderstorm hazard for Sunday. The September 13 Area Forecast Discussion expects only scattered, high-based showers Sunday afternoon, perhaps with a rumble of thunder, and generally less than one-tenth of an inch of rain.

The forecast changes after Monday. Storm chances increase late Monday night, especially north of Interstate 80. On Tuesday afternoon, the front may reach areas along and south of I-80 during peak heating. NWS says storms there could produce torrential downpours and become strong to severe. The outlook assigns Tuesday a Level 1-of-5 severe-thunderstorm risk and an elevated flooding risk. Wednesday and Thursday retain limited thunderstorm and elevated flooding risks, but the location of the heaviest rain remains uncertain.

48 hours before: clear the water path from the ground

The goal is not to make a roof diagnosis before a forecast. It is to remove obvious drainage problems that can turn ordinary runoff into preventable water entry.

• From the ground, look for leaves, seed pods, roofing debris, or vegetation visibly blocking gutter outlets. Do not climb onto a roof or wet ladder to clear them.

• Confirm that downspout extensions are connected and discharge away from the foundation without sending water toward a neighbor or a walking surface.

• Check that ground-level drains, window wells, and exterior stair drains are not covered by leaves or stored items.

• Look for a gutter section that is already sagging, separated, or overflowing during light rain. A visibly loose component should be evaluated before heavier water arrives.

Homeowners in southern service areas can review the Tinley Park storm-inspection guide and the Kankakee and Bradley exterior guide for local contact and inspection information. A forecast area does not prove that any individual address will be affected.

24 hours before: test the systems that handle water

• Test the sump pump using the manufacturer’s instructions and make sure the discharge path is open.

• If there is a battery backup, check its status indicator and the age or condition of the battery.

• Move boxes and valuables away from known basement seepage areas and off the floor.

• Confirm that interior floor drains are accessible and that occupants know where active leaks have appeared before.

• Charge phones and flashlights so you can safely document a problem during a power interruption.

Do not perform electrical work, enter standing water near electrical equipment, or improvise a roof repair during deteriorating weather. Use the NWS flood-preparation guidance for broader household safety planning.

Review known leak and temporary-repair areas

If a ceiling stain, roof penetration, flashing transition, siding opening, or temporary patch has leaked before, photograph its current condition from a safe location. Note the date and whether the surface is presently dry. That baseline makes it easier to explain what changed if water appears later.

A temporary roof covering should remain secured without loose edges or visible openings. Do not step onto the roof to inspect it. If temporary protection appears displaced, contact an experienced provider while conditions are still safe. Read how emergency roof tarping differs from permanent repair.

During the weather: safety outranks documentation

Use current NWS warnings and local emergency alerts. Stay away from windows, flooded roads, fallen limbs, loose exterior materials, and standing water near electrical systems. Never go outside during lightning or high winds to photograph a roof, gutter, or siding panel. The NWS provides additional thunderstorm preparation guidance.

After the rain: record symptoms before guessing at cause

When conditions are safe, begin with wide ground-level photographs of each elevation and roofline. Then record gutter overflow points, displaced materials, water tracks, ceiling changes, or debris impact. Keep original files and note when each condition was first observed.

A water mark, loose shingle, dent, or siding crack does not establish when or why it occurred. Age, installation conditions, prior impacts, and weather can produce similar symptoms. A photo-documented exterior inspection can record accessible construction conditions and help define repair work. A contractor does not determine insurance coverage or interpret a policy.

When to request help

Call promptly if there is active water entry, a visible roof opening, detached material, a sagging ceiling, or a condition you cannot safely evaluate from the ground. Emergency mitigation may reduce additional exposure, while permanent repair should address the actual construction detail after conditions are documented.

Supreme Building Group serves Tinley Park, Kankakee, Bradley, Naperville, Hinsdale, Crystal Lake, Huntley, Orland Park, Lemont, and surrounding Chicagoland communities. For roof, siding, gutter, or emergency-mitigation concerns, call (224) 735-4245.

Sources and update time

This article reflects official information available September 13, 2026. Sources: NWS Chicago Hazardous Weather Outlook, NWS Chicago Area Forecast Discussion, NWS thunderstorm preparation, and NWS flood preparation. Forecasts change; use weather.gov for current warnings and decisions.