WEATHER UPDATE: Fox River Flood Warning Continues; More Rain Memorial Day Weekend

WEATHER UPDATE: Fox River Flood Warning Continues; More Rain Memorial Day Weekend


The Flood Warning for the Fox River at Algonquin Lock & Dam tailwater — or from Johnsburg downstream to Red Gate Road in St. Charles — will continue until further notice, according to a Friday update from the National Weather Service Chicago.

The upcoming Memorial Day weekend is expected to bring more rain.

According to the NWS-C weather story, the weather will be primarily quiet and on the cloudy side today (Friday, May 22), with seasonable temperatures away from the cool lakeshore. The main item of note is the risk for fog, some dense, along the Lake Michigan shore to potentially spread inland tonight.

Memorial Day Weekend will be much warmer and humid inland, with a periodic threat for thunderstorms.

Saturday afternoon and evening at this time appear to have the highest likelihood of thunderstorms, some of which could be strong to severe, along with a risk for very heavy downpours and flooding.

Sunday and especially Monday could then have a threat for some scattered thunderstorms. The warm and humid pattern with a periodic chance for thunderstorms will continue next week.


Fox River Flood Warning Continues

River flooding continues across the area, with moderate to major flooding on several area rivers, according to the National Weather Service Chicago.

Most locations are at or near crest, with conditions expected to slowly improve through the rest of the week, but some areas along the Illinois River are experiencing near record flooding.


The Flood Warning continues for The Fox River at Montgomery — or from Red Gate Road in St. Charles downstream to Millington — until Saturday evening.

At 9:45 a.m. Wednesday, the stage was 13.7 feet. Flood stage is 13.5 feet.

Minor flooding is occurring and minor flooding is forecast.

Forcast: The river will continue to rise near 13.7 feet by Wednesday afternoon. The river will fall below flood stage by Saturday afternoon.

Impact: At 13.5 feet, low-lying parking lots at City Hall and Boy Scout Island are threatened in St. Charles. Fox River Trail is threatened at Mount St. Mary Park in St. Charles.

Algonquin Tailwater

The Flood Warning continues for the Fox River at Algonquin Lock & Dam tailwater — or from Johnsburg downstream to Red Gate Road in St. Charles — until further notice.

At 9:30 a.m. Wednesday, the stage was 11.1 feet. Flood stage is 9.5 feet.

Moderate flooding is occurring, and moderate flooding is forecast.

Forecast: The river will continue rising to near 11.2 feet by Thursday morning. Additional rises may be possible thereafter.

Impact: At 11.0 feet, Filip Street and Fox River Drive threatened in Algonquin.


Flood Warning For Parts of Fox River

The National Weather Service Chicago is continuing its Flood Warning for parts of the Fox River, including two locations in Kane County.

According to the NWS-C, the warning continues for:

  • The Fox River at Montgomery, affecting Kane and Kendall counties.
  • The Fox River at Dayton, affecting La Salle County.
  • The Fox River at Algonquin Lock & Dam tailwater, affecting Kane and McHenry counties.

The forecasts are based on observed precipitation as well as forecast precipitation 24 to 48 hours into the future.



Fast Facts on 4-Day Flooding Event

Flooding was observed across numerous locations in the Chicago Metropolitan Area, especially downtown near the Chicago River, the National Weather Service reports.

The Chicago River rose high enough that the Metropolitan Water Reclamation District, which manages the river, was able to reverse the flow to Lake Michigan.

While flooding was the significant hazard, two reported brief/weak tornadoes also occurred in NWS Chicago’s Warning Area, one along the LaSalle / Kendall County border, second near Grundy / Will County border. There was no significant damage.

Sunday’s 3.11 inches ranks as the fifth wettest May calendar day ever in Chicago.

Two of the five wettest days ever recorded during any May in Chicago have happened in the past week!

Last Thursday’s 3.53 inches of rain broke the record for the wettest calendar day ever in May in Chicago.

Other Information:

  • During the four-day period of May 14-17, Chicago recorded 7.88 inches of rain, making it the fourth wettest four-day stretch in Chicago recorded weather history dating back to 1871.
  • The top four wettest four-day stretches in Chicago are:
    1) 12.84 inches (Aug 13-16, 1987)
    2) 8.61 inches (July 21-24, 2011)
    3) 8.45 inches (Sept 11-14, 2008)
    4) 7.88 inches (May 14-17, 2020)
  • That 7.88 inches of rainfall is more than has fallen during 1,759 of the 1,792 months of weather records in Chicago, only 33 months (less than 2%) have had more rain during the entire month than what fell in just that four-day stretch.
  • May 2020 is only 0.06 inches away from breaking the record for wettest May ever in Chicago (as of 7 a.m. on the 18th, so still nearly two weeks to potentially add to that total).
  • The previous wettest May in Chicago was last year with 8.25 inches. Crazily, prior to last year, the wettest May on record as 2018 with 8.21 inches. So in all likelihood Chicago is about to see back to back to back record breaking wet Mays in Chicago!
  • Finally, prior to the back to back to back record wet Mays, the 7.88 inches of rain that fell May 14-17 would have been enough to break the record rainfall for the entire month of May prior to 2018, all in just four days.

11:30AM MONDAY, May 18

Algonquin Leads With 3.73 Inches of Rain

Here are some preliminary rainfall totals over the last 48 hours, courtesy of the National Weather Service Chicago.

“Observations are collected from a variety of sources with varying equipment and exposures,” the NWS-C says. “We thank all volunteer weather observers for their dedication.”

Not all data listed are considered official. Chicago O’Hare Airport recorded 3.11 inches on the calendar day of May 17 for a total from this event of 3.57 inches.

Interestingly, Chicago O’Hare airport recorded 3.53 inches just a few days ago on May 14 for an impressive two calendar days in one month of over 3 inches of rain.

These saturated conditions were the impetus for the flash flooding observed across the western and southwestern suburbs and in the city of Chicago.

Kane County 48-Hour Totals

  1. Algonquin — 3.73 inches
  2. Lake in the Hills — 3.35 inches
  3. Elburn — 2.87 inches
  4. Elgin — 2.71 inches
  5. North Aurora — 2.45 inches
  6. Batavia —  2.34 inches
  7. Geneva — 2.09 inches
  8. 4 ESE Boulder Hill — 1.92 inches
  9. Aurora — 1.87 inches
  10. Sugar Grove – Aurora Airport — 1.61 inches

48-Hour Regional Totals



Location                     Amount    Time/Date

Palos Heights                4.59 in   0445 AM 05/18
Chicago                      4.54 in   0445 AM 05/18
Midway 3 SW COOP             4.35 in   1200 AM 05/18
Burr Ridge                   4.14 in   0213 AM 05/18
Countryside                  4.04 in   0448 AM 05/18
Joliet                       3.99 in   0445 AM 05/18
Chicago Midway               3.97 in   0353 AM 05/18
Chicago - Garfield Park 2 EN 3.87 in   0441 AM 05/18
Oak Park                     3.86 in   0442 AM 05/18
2 NW Lakeview                3.73 in   0449 AM 05/18
Algonquin                    3.73 in   0449 AM 05/18
Plainfield                   3.72 in   0445 AM 05/18
1 E Albany Park              3.67 in   0449 AM 05/18
Chicago OHare                3.59 in   0451 AM 05/18
1 N Norridge                 3.58 in   0445 AM 05/18
Naperville                   3.57 in   0445 AM 05/18
Hickory Hills                3.56 in   0442 AM 05/18
Wheaton                      3.53 in   0445 AM 05/18
Chicago                      3.52 in   0445 AM 05/18
Union Hill                   3.52 in   0440 AM 05/18
1 WNW Glenview               3.52 in   0450 AM 05/18
Plainfield                   3.49 in   0445 AM 05/18
1 N Chicago Ridge            3.47 in   0450 AM 05/18
Franklin Park                3.46 in   0445 AM 05/18
1 NW Douglas Park            3.44 in   0450 AM 05/18
La Grange                    3.41 in   0430 AM 05/18
Romeoville - NWS Chicago     3.41 in   1200 AM 05/18
Oak Lawn                     3.41 in   0449 AM 05/18
Evergreen Park               3.39 in   0449 AM 05/18
New Lenox                    3.38 in   0446 AM 05/18
Lockport - Chicago Ship Cana 3.37 in   0400 AM 05/18
Lake in the Hills            3.35 in   0445 AM 05/18
1 NNW Navy Pier              3.34 in   0450 AM 05/18
Cary                         3.32 in   0446 AM 05/18
Chicago                      3.32 in   0445 AM 05/18
Oak Lawn                     3.30 in   0448 AM 05/18
1.4 SW Woodridge             3.30 in   0345 AM 05/18
Oak Lawn                     3.24 in   0450 AM 05/18
Lyons                        3.23 in   0449 AM 05/18
1 NNW Midway Airport         3.22 in   0449 AM 05/18
Burbank                      3.22 in   0445 AM 05/18
1 WNW Merrionette Park       3.21 in   0450 AM 05/18
Lakeview                     3.18 in   0449 AM 05/18
Palos Heights                3.18 in   0450 AM 05/18
Maywood                      3.17 in   0450 AM 05/18
2 NNE Tinley Park            3.17 in   0450 AM 05/18
Lincoln Park                 3.13 in   0450 AM 05/18
Midway Airport               3.12 in   0450 AM 05/18
Libertyville                 3.09 in   0447 AM 05/18
Rogers Park                  3.09 in   0449 AM 05/18
2 S Jefferson Park           3.07 in   0449 AM 05/18
1 WNW Logan Square           3.06 in   0449 AM 05/18
Albany Park                  3.04 in   0449 AM 05/18
Lakeview                     3.02 in   0449 AM 05/18
Joliet                       3.00 in   0448 AM 05/18
Indiana Dunes RAWS           3.00 in   0417 AM 05/18
Alsip                        2.99 in   0449 AM 05/18
Joliet                       2.99 in   0449 AM 05/18
1 SW Albany Park             2.97 in   0449 AM 05/18
Joliet                       2.97 in   0440 AM 05/18
River Grove                  2.95 in   0450 AM 05/18
Griffith                     2.93 in   0449 AM 05/18
1 S Lincoln Park             2.92 in   0450 AM 05/18
Peotone                      2.92 in   0441 AM 05/18
Griffith                     2.92 in   0445 AM 05/18
Naperville                   2.92 in   0445 AM 05/18
2 ENE Evergreen Park         2.91 in   0450 AM 05/18
Plainfield                   2.91 in   0449 AM 05/18
Rosemont                     2.91 in   0445 AM 05/18
1 SSW Winnetka               2.91 in   0450 AM 05/18
Flossmoor                    2.89 in   0450 AM 05/18
Midewin RAWS                 2.89 in   0405 AM 05/18
Vernon Hills                 2.88 in   0443 AM 05/18
Elburn                       2.87 in   0445 AM 05/18
York Center                  2.87 in   0450 AM 05/18
Crestwood                    2.87 in   0450 AM 05/18
1 N Jefferson Park           2.86 in   0449 AM 05/18
Naperville                   2.86 in   0445 AM 05/18
2 SSW Burr Ridge             2.85 in   0450 AM 05/18
Glenview                     2.81 in   0446 AM 05/18
Lake Forest                  2.80 in   0447 AM 05/18
Orland Park                  2.80 in   0450 AM 05/18
Westmont                     2.78 in   0448 AM 05/18
Lake Bluff                   2.78 in   0447 AM 05/18
Hillside                     2.76 in   0450 AM 05/18
Elburn                       2.73 in   0450 AM 05/18
Westchester                  2.72 in   0449 AM 05/18
Elgin                        2.71 in   0447 AM 05/18


River Flooding Today (Monday, May 18)

Heavy rainfall expected later this afternoon and tonight will likely cause new river rises and possible flooding, the National Weather Service Chicago reports.

Major flooding may be possible in some areas, depending on the exact location of heavy rainfall. Latest river forecasts:

Scattered Showers Ahead

After Sunday’s heavy rain and flooding, a quieter period of weather is expected this week, the NWS says.

Lingering effects from the low pressure system on Sunday will result in isolated to scattered showers through Tuesday, though heavy rain is not expected.

Conditions will gradually warm mid to late week.



Thunderstorms with torrential downpours continue to move to the northeast at around 45 mph, the National Weather Service reported at 2:50 p.m. today (Sunday, May 17, 2020).

Flash flooding may occur with the storms.

Isolated, brief tornadoes are also possible, mainly along and south of I-88 and east of I-39 in the next few hours. The western end of the tornado threat will gradually shift eastward as well. Be alert for possible warnings. Avoid low lying, flood prone areas and do not enter flood waters.


Flash Flood Watch Sunday

A Flash Flood Watch is now in effect through this evening for Kane County and other portions of Illinois and northwest Indiana.

According to the National Weather Service Chicago, we an expect widespread light to moderate rain with a few embedded thunderstorms will continue through this morning, with a possible brief reduction in coverage mid morning.

A slow-moving line of heavy showers and thunderstorms this afternoon will likely produce a period of heavy rain, with 1 to 2 inches of rain possible over a period of less than two hours.

The NWS says rain will fall onto soils that are saturated due to Thursday night`s heavy rain event and additional rainfall since last evening. Widespread total rainfall amounts from last evening through this evening will total 1.5 to 2.5 inches, with localized amounts in excess of 3 inches.

This heavy rainfall may result in flooding, especially of low lying or poor drainage areas. The main concern period is this afternoon into this evening. Additional rises on area rivers will continue into the upcoming work week.

A Flash Flood Watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation. You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued.

Moderate To Heavy Rain

The potential for heavy rain continues today, especially this afternoon when thunderstorms will be capable of producing rain rates of over 1 inch per hour.

With soils already saturated, the heavy rain will result in an increased flash flooding risk through this evening. Renewed rises on area rivers are also likely.

Severe Thunderstorm Potential

Thunderstorms are expected to develop as a slow-moving line this afternoon. Some of these thunderstorms may become strong to severe, with brief tornadoes and isolated damaging wind gusts possible.

The greatest risk exists from 2 p.m. to 7 p.m.  primarily south of I-88 and east of I-39, including southern portions of the Chicago metro.

Minor Lakeshore Flooding

Strong and gusty northeast winds will develop late tonight into Monday, resulting in building wave action.

These higher waves, combined with the near record lake levels are expected to result in a period of mainly minor lakeshore flooding Monday into Monday night.