County annual report · FIPS 17031
2021 Cook County, IL Power Outage Report
In 2021, customers in Cook County, IL went without power for an average of 1.6 hours, a total of 3.5M customer-hours (Illinois average 2.3 hours). That ranks 79th worst of 102 Illinois counties and 2396th of 2,974 nationally.
Compared with IL, the US and 2020
Coverage line is EAGLE-I's share of Illinois customers tracked each year.
Biggest outages in Cook County, 2021
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | August 2, 2021 11:15 | August 23, 2021 10:45 | 20d 23h | 73,829 | 1.1M |
| 2 | July 10, 2021 11:15 | August 2, 2021 09:30 | 22d 22h | 22,644 | 279K |
| 3 | October 24, 2021 11:45 | November 15, 2021 07:30 | 21d 19h | 20,640 | 280K |
| 4 | December 9, 2021 13:15 | December 24, 2021 07:00 | 14d 17h | 17,712 | 226K |
| 5 | August 23, 2021 11:45 | September 19, 2021 10:00 | 26d 22h | 16,341 | 209K |
| 6 | May 20, 2021 10:00 | July 10, 2021 10:30 | 51d | 15,993 | 667K |
| 7 | March 29, 2021 10:30 | April 12, 2021 04:00 | 13d 17h | 15,418 | 87K |
| 8 | April 25, 2021 12:15 | May 7, 2021 01:30 | 11d 13h | 4,134 | 78K |
| 9 | November 27, 2021 12:00 | December 1, 2021 09:30 | 3d 21h | 2,902 | 9,662 |
| 10 | January 25, 2021 09:15 | January 25, 2021 12:30 | 3h 15m | 2,873 | 2,200 |
Outage episodes by size in 2021: 66 reached 100+ customers, 36 reached 1,000+ customers, 7 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 2021, 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 | 2021 | 1.7 hrs | 0.77 | 43 min | 0.59 |
| Northern Indiana Pub Serv Co | 2021 | 8.8 hrs | 1.55 | 2.9 hrs | 1.06 |
| 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 98% of Illinois's customers in 2021; 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, 2021, 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/2021/illinois/cook-county