County annual report · FIPS 17031
2025 Cook County, IL Power Outage Report
In 2025, customers in Cook County, IL went without power for an average of 1.4 hours, a total of 3.0M customer-hours (Illinois average 2.5 hours). That ranks 87th worst of 102 Illinois counties and 2652nd of 3,000 nationally.
Compared with IL, the US and 2024
Coverage line is EAGLE-I's share of Illinois customers tracked each year.
Biggest outages in Cook County, 2025
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | May 11, 2025 23:00 | May 19, 2025 07:00 | 7d 8h | 63,645 | 776K |
| 2 | August 7, 2025 11:45 | August 25, 2025 07:00 | 17d 19h | 44,656 | 744K |
| 3 | July 21, 2025 13:30 | August 4, 2025 04:00 | 13d 14h | 29,730 | 325K |
| 4 | June 2, 2025 11:15 | July 7, 2025 10:30 | 34d 23h | 10,875 | 224K |
| 5 | July 7, 2025 11:30 | July 21, 2025 12:30 | 14d 1h | 6,358 | 81K |
| 6 | March 13, 2025 10:45 | March 20, 2025 20:30 | 7d 9h | 5,596 | 54K |
| 7 | March 23, 2025 13:45 | April 6, 2025 13:00 | 13d 23h | 5,269 | 61K |
| 8 | November 24, 2025 06:30 | November 29, 2025 12:30 | 5d 6h | 5,080 | 36K |
| 9 | November 2, 2025 13:30 | November 14, 2025 15:00 | 12d 1h | 4,289 | 37K |
| 10 | September 8, 2025 04:15 | September 22, 2025 05:30 | 14d 1h | 4,102 | 58K |
Outage episodes by size in 2025: 84 reached 100+ customers, 35 reached 1,000+ customers, 4 reached 10,000+ customers.
Utility reliability filed with the EIA
SAIDI (average outage time per customer) and SAIFI (average interruptions per customer) that utilities serving Cook County reported on EIA Form 861 for 2025, or their most recent earlier filing. Utility-wide figures, not county-specific.
| Utility | EIA year | SAIDI | SAIFI | SAIDI excl. major events | SAIFI excl. major events |
|---|---|---|---|---|---|
| Commonwealth Edison Co | 2024 | 2.2 hrs | 0.68 | 36 min | 0.49 |
| Northern Indiana Pub Serv Co | 2024 | 8.9 hrs | 1.34 | 2.8 hrs | 0.97 |
| University of Illinois | - | - | - | - | - |
| Village of Winnetka - (IL) | - | - | - | - | - |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about n/a of Illinois's customers in 2025; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 2,162,007 customers (ORNL modeled county customer count), including major storm days. It is comparable across counties but is not the SAIDI a utility files.
- An outage event is a continuous stretch with customers out; counts at 100, 1,000 and 10,000+ use its peak.
- Years loaded: 2015–2025. Cook County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), Cook County, IL annual power outage report, 2025, data as of Oct 3, 2026 02:41 UTC, sources: DOE EAGLE-I (https://eagle-i.doe.gov/); EAGLE-I modeled customer counts (MCC) (https://figshare.com/); EIA Form 861 (utility reliability) (https://www.eia.gov/electricity/data/eia861/). https://massoutage.com/reports/2025/illinois/cook-county