[3:38 PM 7/15] Clusters of showers and some storms will gradually develop and push northward this afternoon. Severe weather is not expected, but gusty winds and brief downpours will be possible with the strongest storms. Activity should diminish through the evening. #ILwx #INwx

[2:30 PM 7/15/2025] Periodic thunderstorm chances exist through Thursday and again over the weekend, along with typical summertime heat and humidity. Strengthening winds on Thursday will result in building waves and dangerous swim conditions on the lake into Friday. #ILwx #INwx

[2:30 PM 7/15/2025] An Air Quality Alert is now in effect through Wed. evening for the Chicago metro area and in NW Indiana due to unhealthy ozone levels and some lingering effects of Canadian wildfire smoke. Air quality is expected to be at unhealthy levels for sensitive groups.

[2:30 PM 7/15/2025]There is a threat for scattered strong to severe thunderstorms capable of producing corridors of wind damage on Wednesday afternoon and early evening. In addition, torrential downpours may cause localized flooding. Stay tuned for updates! #ILwx #INwx

One year ago today, a powerful derecho impacted the region, producing widespread damaging winds & a record-breaking number of tornadoes in both the state of Illinois (48) as well as the 23 counties that our office serves (32). More info here: #ILwx #INwx

Periods of increased humidity and thunderstorm chances are expected through the remainder of the week and into the weekend. Strong to severe thunderstorms will be possible on Wednesday, along with afternoon heat indices near 100°F. #ILwx #INwx

Thunderstorms are expected in the region on Wednesday. The strongest storms could cause damaging winds and flash flooding, though there is still uncertainty in the exact coverage of storms and where the greatest threat for severe storms and flooding will end up being. #ILwx #INwx

For our last post on July 1995 heat wave material, more info on why the dew point temp is an excellent quantifier for how an air mass feels in summer (h/t @NWSTampaBay) We also recently updated our local Heat Safety and Preparedness page: #ILwx #INwx

Enhanced evapotranspiration leads to increased moisture emitted into the air, resulting in higher dew points & humidity. Thus, the above normal rainfall observed in the Corn Belt region in May 1995 likely played a role in the extreme dew points in mid-July 1995. #ILwx (7/7).

A 2003 research paper found that late spring rainfall anomalies in the "Corn Belt" region of the Midwest correlate to increased levels of evapotranspiration from crops during the mid-late summer. #ILwx (6/7).

A factor that likely contributed to the intensity of the heat wave was an abnormally wet May of 1995, particularly across the vast "Corn (and soybean) Belt" region. #ILwx (5/7)

Regional peak heat indices, high temperatures, and peak dew points on July 14, 1995. #ILwx (4/7)

Regional peak heat indices, high temperatures, and peak dew points on July 13, 1995. #ILwx (3/7)

Timelines of temperature, dew point, and apparent temperature/heat index observations from July 10 through July 17, 1995 at #Chicago O'Hare Airport, Midway Airport, Meigs Field (de-commissioned airport on Northerly Island), and Rockford Airport. #ILwx (2/8)

Maximum daytime temperatures (in degrees Fahrenheit) at Chicago-area reporting stations on July 13 and 14, 1995. Source: NOAA/NWS July 1995 National Disaster Survey Report. #ILwx (1/8)

Heat and humidity will build back into the region for the midweek period, bringing a return to periodic thunderstorm chances particularly Wednesday afternoon into Thursday. Some of the storms on Wednesday evening may be strong. Stay tuned for updates! #ILwx #INwx

An Air Quality Alert is in effect through Tuesday evening for the Chicago metro area in Illinois and in northwest Indiana due to unhealthy ozone levels and some lingering effects of Canadian wildfire smoke. #ILwx #INwx

To recognize the 30-year anniversary of this historic event, we published an extensive update (multiple newly created maps, graphics, and some new content) of our event recap webpage, .#ILwx (4/4)

Then on 7/14/1995, #Chicago-O'Hare observed another daily record high of 100°, a record warm "low" of 83°, and a peak hourly heat index of 116°. Midway Airport had a high of 102°, a "low" of 84°, and a peak hourly heat index of 119° on July 14th. #ILwx (3/4).

7/13/1995 was the most oppressive day of the heat wave. #Chicago-O'Hare (Chicago's official climate site), had a daily record high temp of 104°, a record warm low temp of 81°, & a peak heat index of 118°. Chicago-Midway a high of 106° & a peak heat heat index of 124°! #ILwx (2/4)