ComEd and Argonne National Laboratory Release Study Showing Severe Rainfall Events in Northern Illinois Could Nearly Double in Next 15 Years

Research identifies increasing risks from heavier rainfall, ice storms and changing soil conditions that could have a major impact on electric infrastructure across northern Illinois

CHICAGO--(BUSINESS WIRE)--ComEd today announced the release of a new severe weather study that presents the most detailed picture ever of the climate conditions taking shape in northern Illinois. The study, conducted in partnership with the U.S. Department of Energy’s Argonne National Laboratory, analyzes weather patterns in the region, seeking to learn how they may impact communities and critical infrastructure.

Among the findings, the study projects that the number of heavy rainfall events in northern Illinois, defined as those producing more than two inches of precipitation, could nearly double by mid-century. Annual precipitation across ComEd’s service territory could increase by an average of 14.7 percent, underscoring the need for additional investments to maintain grid resilience in the face of growing climate risks.

“Understanding how severe weather could change in the decades ahead is critical to making the right investments today,” said Gil C. Quiniones, president and CEO of ComEd. “This research gives us a clearer picture of the risks our communities and infrastructure may face and will help inform how we continue strengthening the grid to deliver reliable, resilient and affordable energy for our customers.”

Commissioned by ComEd and conducted by Argonne researchers using advanced climate modeling and localized weather projections, the study examines projected changes in precipitation, ice storms, soil moisture, soil temperature and solar irradiance across northern Illinois. The findings look at conditions for 2045-2054 and reveal a significant increase in severe weather conditions by mid-century.

The study provides grid planners with highly localized insights into where changing weather conditions may be most pronounced across northern Illinois, including areas where multiple climate risks could converge. That level of detail can allow ComEd to incorporate future weather risks into long-term planning, engineering standards, asset management strategies and reliability investments.

Key findings from the research include:

• Heavier rainfall, combined with longer dry periods, could increase runoff and flooding risks, including erosion around pole bases and tower footings and added strain on access roads, culverts and substation drainage systems.
• More frequent severe ice events could also place additional stress on electric equipment and increase the risk of tree damage to lines and poles.
• Increased soil moisture could affect underground cables, grounding systems and corrosion, while warmer soil temperatures could make it more difficult for underground lines to release heat.

“As severe weather evolves, utilities need increasingly detailed information to understand how those changes could affect infrastructure and communities,” said Argonne laboratory director Paul Kearns. "By combining advanced climate projections with localized analysis, this work helps translate scientific insights into practical decision-making tools that can strengthen resilience for communities across northern Illinois."

The new findings come as northern Illinois experiences one of the most active severe weather periods in recent history. This year alone, the region has experienced 19 major storms, 59 tornadoes, and approximately 2.4 million customer interruptions, making 2026 ComEd's most severe storm season on record. Despite these challenges, previous grid modernization investments helped avoid an estimated 2.6 million additional customer interruptions and supported faster restoration efforts following major weather events.

The latest study builds on a 2022 partnership between ComEd and Argonne that examined future temperature trends and found that as soon as 2045, northern Illinois is expected to experience climate conditions more similar to those currently found in Missouri and southern Illinois. That earlier research projected hotter temperatures, longer growing seasons, higher humidity, and more frequent heat waves, conditions that can accelerate equipment aging, increase vegetation management needs and place additional demands on the electric system.

Insights from earlier research have contributed to ComEd's broader understanding of climate-related risks and have helped inform discussions supporting long-term grid planning efforts, including its recently filed Multi-Year Integrated Grid Plan. The utility expects the new findings to further shape future reliability and resilience investments designed to prepare the grid for evolving weather conditions while continuing to support customer affordability, reliability and economic growth.

ComEd is a unit of Chicago-based Exelon Corporation (NASDAQ: EXC), a Fortune 200 company and one of the nation’s largest utility companies, serving roughly 11 million electricity and natural gas customers. ComEd powers the lives of more than 4 million customers across northern Illinois, or 70 percent of the state’s population. For more information, visit ComEd.com, and connect with the company on Facebook, Instagram, LinkedIn, X and YouTube.

Argonne National Laboratory is a U.S. Department of Energy national laboratory that delivers scientific discoveries and technological innovations to address critical national challenges in energy, security and resilience. Through advanced climate modeling and decision science, Argonne helps organizations better understand and prepare for future risks.