Flood Warning Issued for Kane, Lake, and McHenry Counties in Illinois

Source: NOAA · Northeastern Illinois

If you are in immediate danger, call emergency services now.

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The National Weather Service in Chicago has issued a Flood Warning for Kane, Lake, and McHenry counties in Illinois, with minor flooding expected along the Fox River from Tuesday afternoon to Saturday evening.

What this NWS weather alert tells you, and what most readers miss

This notice was issued by NOAA on April 7, 2026 and geographically references Northeastern Illinois. Its severity classification of "high" signals how the issuing agency weighs the risk of harm if no action is taken - "critical" and "high" tier alerts typically carry direct consumer actions, while "medium" and "low" tend toward informational guidance or monitoring advisories. The category it belongs to - Weather Alerts - determines the warning protocol behind it, which shapes what protective action (seeking shelter, following evacuation orders if issued, monitoring official updates) is recommended and which agency holds authority to issue or cancel it.

Most readers skim a notice like this, check whether they are personally affected, and move on. The more useful lens is to read it as a data point about the issuing system: how quickly NOAA detected the hazard, how precise the geographic or product-identifier scope is, and whether similar notices have clustered in the same category or region in the last 90 days. Cluster patterns frequently precede a broader regulatory action, a single localized NWS weather alert is isolated; three of them within a quarter often indicate a supply-chain, infrastructure, or seasonal driver that will keep producing notices until something structural changes.

For decision-making, Areazine pairs each alert with the original agency URL, the full agency name, and a timestamp so you can verify the notice against the primary source before acting on it. Tags on this item (weather, alert, FloodWarning, Illinois) map to related alerts in the same area of risk - browsing them together gives a clearer picture than any single notice alone, because the shape of an ongoing issue only becomes visible across multiple sequential alerts.

Alert Details

The Flood Warning has been issued by the National Weather Service (NWS) Chicago IL. It is effective from April 6, 2026, at 8:26 PM CDT, with onset at April 7, 2026, at 1:00 PM CDT.

Affected Areas

The warning affects Kane, IL; Lake, IL; and McHenry, IL counties. Specifically, it impacts the Fox River from Johnsburg downstream to Red Gate Road in St. Charles, including the Algonquin Lock & Dam tailwater gauge.

What You Should Do

Persons along rivers and streams in the warned area should take immediate precautions to protect life and property. Avoid the affected areas as flooding is imminent or occurring.

Expected Conditions

Minor flooding is forecast. The river stage is currently at 9.4 feet and is expected to rise above the flood stage of 9.5 feet to a crest of 9.7 feet on Wednesday evening.

Timeline

The alert is effective from April 7, 2026, at 1:00 PM CDT (onset) and ends on April 11, 2026, at 7:00 PM CDT. It expires on April 7, 2026, at 2:30 PM CDT.

Original source: NOAA Official Notice ↗

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Frequently Asked Questions

Common questions about this NWS weather alert.

What is this NWS weather alert about?
The National Weather Service in Chicago has issued a Flood Warning for Kane, Lake, and McHenry counties in Illinois, with minor flooding expected along the Fox River from Tuesday afternoon to Saturday evening.
Which agency issued this alert?
This alert was issued by NOAA. The original notice is available at the source link at the bottom of this article.
How severe is this alert?
This alert is classified as "high" severity. Take precautions and monitor for updates.
What area is affected?
This alert affects Northeastern Illinois. Check with NOAA for the most current geographic scope.
Where can I find more Weather Alerts updates?
Browse the full Weather Alerts feed on Areazine at areazine.com/weather/ for the latest updates from NOAA and other agencies.