Cook County, IL

Alerts

Watch Area
Advisory Area
County Line

Alerts are listed in order of start time and level of severity. Click on the alert title to read details for each alert.

In effect from Sunday 09/20 7:00 AM CDT – Tuesday 09/22 7:00 PM CDT

Issued by NWS Chicago IL

What

High wave action and dangerous currents expected at Lake Michigan beaches. Waves 7 to 10 ft expected.

Where

Northern Cook and Central Cook Counties.

When

From Sunday morning through Tuesday evening.

Impacts

Swimming conditions will be life threatening, especially for inexperienced swimmers.

What to Do

Remain out of the water to avoid dangerous swimming conditions and do not venture out onto piers, jetties, breakwalls, or other shoreline structures.


Areas Impacted

  • Northern Cook
  • Central Cook

Tips to Stay Safe

Your area may see dangerous swimming conditions. Use caution: 

  • Stay off of rocks and jetties due to dangerous conditions
  • Stay out of the water to avoid hazardous swimming conditions, and stay near occupied lifeguard towers 
  • Keep small children in sight and within arm’s reach at all times.

In effect from Saturday 09/19 3:57 PM CDT – Sunday 09/20 7:00 AM CDT

Issued by NWS Chicago IL

What

Flash flooding caused by excessive rainfall continues to be possible.

Where

Portions of Illinois, including the following areas, Boone, Central Cook, De Kalb, DuPage, Kane, Kendall, Lake IL, Lee, McHenry, Northern Cook, Northern Will, Ogle, Southern Cook and Winnebago and northwest Indiana, including the following areas, Lake IN and Porter.

When

Through early Sunday morning.

Impacts

Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. Roads and streets may be flooded.

Additional Details

- Showers and thunderstorms, some with torrential rainfall with hourly rates around 2 inches per hour, are expected to redevelop across the watch area this evening and overnight. Repeated rounds of heavy rainfall may result in areas of flash flooding and rapid rises on area rivers. - http://www.weather.gov/safety/flood

What to Do

A Flood Watch for flash flooding means rapid-onset flooding is possible, but not yet certain, based upon the latest forecasts. Flash flooding is a dangerous situation. Persons with interests along area rivers, creeks, and other waterways should monitor the latest forecasts and be prepared to take action should flooding develop.


Areas Impacted

  • Winnebago
  • Boone
  • McHenry
  • Lake
  • Ogle
  • Lee
  • De Kalb
  • Kane
  • DuPage
  • Kendall
  • Northern Cook
  • Central Cook
  • Southern Cook
  • Northern Will
  • Lake
  • Porter

Tips to Stay Safe

A Flood Watch means the area may experience a dangerous flooding event, and being prepared may save lives and property. 

  • Be aware of low-lying areas along your travel routes that are most likely to flood. 
  • Check your home’s emergency supplies, and make sure all members of the household know your emergency plan
  • Stay tuned for local weather updates on the situation as it develops.

If a Flood Warning is issued, it means that dangerous flooding is expected or already happening. 

  • Never walk, swim, or drive through flood waters or flooded roads. 
  • Stay away from areas where water levels can rise rapidly, like storm drains, culverts, creeks and streams. 

If your home is likely to flood, or if authorities tell you to evacuate, do so immediately and move to higher ground. 

In effect from Sunday 09/20 7:00 AM CDT – Sunday 09/20 3:45 AM CDT

Issued by NWS Chicago IL

The National Weather Service in Chicago has issued a Flood Watch for the following rivers in Illinois

Des Plaines River near Russell affecting Lake IL County.

Des Plaines River near Gurnee affecting Lake IL County.

Des Plaines River at Lincolnshire affecting Cook and Lake IL County.

Des Plaines River near Des Plaines affecting Cook County.

Des Plaines River at Riverside affecting Cook County.

.The combination of heavy rain this morning and expected additional thunderstorms with heavy rain tonight may lead to river flooding along the Des Plaines River basin as early as Sunday morning. The heavy rain tonight is expected to occur along a roughly west to east axis across northern Illinois, though the exact location across the river basin remains uncertain. Flooding severity may be higher or lower over the basin depending on the ultimate placement of the highest rainfall tonight.

What

Flooding is possible.

Where

Des Plaines River from Palatine Road in Prospect Heights downstream to Irving Park Road in Chicago, including the Des Plaines gauge.

When

From Sunday morning until further notice.

Additional Details

- At 8:45 AM CDT Saturday the stage was 10.1 feet. - Forecast...Flood stage may be reached based on the latest forecast information. - Flood stage is 15.0 feet. - http://www.weather.gov/safety/flood

What to Do

A Flood Watch means water levels above flood stage are possible, but not yet certain, based upon the latest forecasts. Persons along rivers and streams in the watch area should monitor the latest forecasts and be prepared to take action should flooding develop.
These forecasts are based on observed precipitation as well as forecast precipitation 24 hours into the future. Changes to the rainfall forecast, or any additional rainfall after 24 hours, may cause changes to these river forecasts.
Additional information is available at www.weather.gov.
The next statement will be issued by late tonight.


Areas Impacted

  • Northern Cook
  • Central Cook

Tips to Stay Safe

A Flood Watch means the area may experience a dangerous flooding event, and being prepared may save lives and property. 

  • Be aware of low-lying areas along your travel routes that are most likely to flood. 
  • Check your home’s emergency supplies, and make sure all members of the household know your emergency plan
  • Stay tuned for local weather updates on the situation as it develops.

If a Flood Warning is issued, it means that dangerous flooding is expected or already happening. 

  • Never walk, swim, or drive through flood waters or flooded roads. 
  • Stay away from areas where water levels can rise rapidly, like storm drains, culverts, creeks and streams. 

If your home is likely to flood, or if authorities tell you to evacuate, do so immediately and move to higher ground. 

In effect from Sunday 09/20 10:00 AM CDT – Tuesday 09/22 7:00 AM CDT

Issued by NWS Chicago IL

The National Weather Service in Chicago has issued a Flood Watch for the following rivers in Illinois

Des Plaines River near Russell affecting Lake IL County.

Des Plaines River near Gurnee affecting Lake IL County.

Des Plaines River at Lincolnshire affecting Cook and Lake IL County.

Des Plaines River near Des Plaines affecting Cook County.

Des Plaines River at Riverside affecting Cook County.

.The combination of heavy rain this morning and expected additional thunderstorms with heavy rain tonight may lead to river flooding along the Des Plaines River basin as early as Sunday morning. The heavy rain tonight is expected to occur along a roughly west to east axis across northern Illinois, though the exact location across the river basin remains uncertain. Flooding severity may be higher or lower over the basin depending on the ultimate placement of the highest rainfall tonight.

What

Flooding is possible.

Where

Des Plaines River from Roosevelt Road in Forest Park downstream to Hodgkins, including the Riverside gauge.

When

From Sunday morning to Tuesday morning.

Additional Details

- At 8:45 AM CDT Saturday the stage was 3.2 feet. - Forecast...Flood stage may be reached late Sunday morning. - Flood stage is 7.5 feet. - http://www.weather.gov/safety/flood

What to Do

A Flood Watch means water levels above flood stage are possible, but not yet certain, based upon the latest forecasts. Persons along rivers and streams in the watch area should monitor the latest forecasts and be prepared to take action should flooding develop.
These forecasts are based on observed precipitation as well as forecast precipitation 24 hours into the future. Changes to the rainfall forecast, or any additional rainfall after 24 hours, may cause changes to these river forecasts.
Additional information is available at www.weather.gov.
The next statement will be issued by late tonight.


Areas Impacted

  • Central Cook

Tips to Stay Safe

A Flood Watch means the area may experience a dangerous flooding event, and being prepared may save lives and property. 

  • Be aware of low-lying areas along your travel routes that are most likely to flood. 
  • Check your home’s emergency supplies, and make sure all members of the household know your emergency plan
  • Stay tuned for local weather updates on the situation as it develops.

If a Flood Warning is issued, it means that dangerous flooding is expected or already happening. 

  • Never walk, swim, or drive through flood waters or flooded roads. 
  • Stay away from areas where water levels can rise rapidly, like storm drains, culverts, creeks and streams. 

If your home is likely to flood, or if authorities tell you to evacuate, do so immediately and move to higher ground. 

In effect from Sunday 09/20 4:00 PM CDT – Sunday 09/20 3:45 AM CDT

Issued by NWS Chicago IL

The National Weather Service in Chicago has issued a Flood Watch for the following rivers in Illinois

Des Plaines River near Russell affecting Lake IL County.

Des Plaines River near Gurnee affecting Lake IL County.

Des Plaines River at Lincolnshire affecting Cook and Lake IL County.

Des Plaines River near Des Plaines affecting Cook County.

Des Plaines River at Riverside affecting Cook County.

.The combination of heavy rain this morning and expected additional thunderstorms with heavy rain tonight may lead to river flooding along the Des Plaines River basin as early as Sunday morning. The heavy rain tonight is expected to occur along a roughly west to east axis across northern Illinois, though the exact location across the river basin remains uncertain. Flooding severity may be higher or lower over the basin depending on the ultimate placement of the highest rainfall tonight.

What

Flooding is possible.

Where

Des Plaines River from Townline Road in Libertyville downstream to Palatine Road in Prospect Heights, including the Lincolnshire gauge.

When

From Sunday afternoon until further notice.

Additional Details

- At 8:45 AM CDT Saturday the stage was 7.6 feet. - Forecast...Flood stage may be reached Sunday afternoon. - Flood stage is 12.5 feet. - http://www.weather.gov/safety/flood

What to Do

A Flood Watch means water levels above flood stage are possible, but not yet certain, based upon the latest forecasts. Persons along rivers and streams in the watch area should monitor the latest forecasts and be prepared to take action should flooding develop.
These forecasts are based on observed precipitation as well as forecast precipitation 24 hours into the future. Changes to the rainfall forecast, or any additional rainfall after 24 hours, may cause changes to these river forecasts.
Additional information is available at www.weather.gov.
The next statement will be issued by late tonight.


Areas Impacted

  • Lake
  • Northern Cook

Tips to Stay Safe

A Flood Watch means the area may experience a dangerous flooding event, and being prepared may save lives and property. 

  • Be aware of low-lying areas along your travel routes that are most likely to flood. 
  • Check your home’s emergency supplies, and make sure all members of the household know your emergency plan
  • Stay tuned for local weather updates on the situation as it develops.

If a Flood Warning is issued, it means that dangerous flooding is expected or already happening. 

  • Never walk, swim, or drive through flood waters or flooded roads. 
  • Stay away from areas where water levels can rise rapidly, like storm drains, culverts, creeks and streams. 

If your home is likely to flood, or if authorities tell you to evacuate, do so immediately and move to higher ground. 

Briefing

Last updated

From the Forecaster

Threat for Flash Flooding Tonight

Created by the NWS Chicago WFO

Showers and thunderstorms with torrential downpours are expected to develop again across northern Illinois this evening and continue into Sunday morning. This rain will fall over already saturated ground from the past day, increasing the risk for localized flooding in poor drainage, low-lying areas, and urban areas.

Headline: Threat for Flash Flooding Tonight.  Sub Headline: Main time window for flash flooding late this evening through into Sunday morning.  What To Expect.  Another round of torrential rainfall.  May flood roads, low-lying areas, fields, and basements, and cause rapid stream/creek rises. When: Favored Timing of Highest Rainfall Rates.  ~7 PM this evening - 6 AM CDT Sunday.  Where: Areawide. Highest rainfall amounts and greatest flooding impacts favored across northern Illinois and far northwest Indiana, which aligns with much of the area that experienced heavy rain over the past day. What To Do. NEVER drive or walk across flooded roads! Move valuables from flood-prone areas, such as basements and outdoor areas with poor drainage. Graphic Created: Saturday, September 19, 2026 2:27 PM CDT

Seven-day Weather Risk Overview

The graphic shows the daily risk summary for 7 days. Daily risk is based on highest risk factor for that day.

risk level
out of 10
out of 10
out of 10
table legend
No risk
Low risk
High risk

Weather Forecasting Office

Chicago Forecast Office

Find a Forecast

Saved locations