County annual report · FIPS 17111
2021 McHenry County, IL Power Outage Report
In 2021, customers in McHenry County, IL went without power for an average of 7.9 hours, a total of 954K customer-hours (Illinois average 2.3 hours). That ranks 7th worst of 102 Illinois counties and 943rd 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 McHenry 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 10, 2021 09:15 | August 14, 2021 11:30 | 4d 2h | 30,959 | 753K |
| 2 | August 16, 2021 17:00 | August 17, 2021 02:15 | 9h 15m | 5,463 | 5,301 |
| 3 | July 29, 2021 06:00 | July 30, 2021 04:00 | 22h | 5,402 | 31K |
| 4 | June 12, 2021 01:15 | June 12, 2021 14:00 | 12h 45m | 5,026 | 1,624 |
| 5 | September 7, 2021 18:30 | September 8, 2021 18:30 | 1d | 4,481 | 19K |
| 6 | December 15, 2021 22:45 | December 17, 2021 05:45 | 1d 7h | 3,667 | 29K |
| 7 | December 14, 2021 12:30 | December 14, 2021 17:30 | 5h | 1,686 | 926 |
| 8 | October 25, 2021 00:00 | October 26, 2021 07:30 | 1d 7h | 1,685 | 12K |
| 9 | May 1, 2021 17:45 | May 2, 2021 11:30 | 17h 45m | 1,487 | 3,791 |
| 10 | October 3, 2021 07:45 | October 3, 2021 17:30 | 9h 45m | 1,247 | 2,275 |
Outage episodes by size in 2021: 117 reached 100+ customers, 15 reached 1,000+ customers, 1 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 McHenry 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 |
| Rock Energy Cooperative | 2021 | 43 min | 0.47 | - | - |
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 ÷ 120,381 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. McHenry County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), McHenry 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/mchenry-county