County annual report · FIPS 17199
2025 Williamson County, IL Power Outage Report
In 2025, customers in Williamson County, IL went without power for an average of 14.6 hours, a total of 522K customer-hours (Illinois average 2.5 hours). That ranks 8th worst of 102 Illinois counties and 521st 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 Williamson 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 | January 5, 2025 13:15 | January 12, 2025 04:30 | 6d 15h | 10,894 | 416K |
| 2 | May 16, 2025 21:30 | May 21, 2025 21:00 | 4d 23h | 5,741 | 44K |
| 3 | April 5, 2025 00:00 | April 5, 2025 17:00 | 17h | 4,393 | 4,170 |
| 4 | April 7, 2025 20:00 | April 8, 2025 01:15 | 5h 15m | 3,638 | 1,450 |
| 5 | May 14, 2025 12:45 | May 14, 2025 22:00 | 9h 15m | 2,394 | 2,037 |
| 6 | October 8, 2025 20:00 | October 8, 2025 21:30 | 1h 30m | 1,992 | 2,007 |
| 7 | July 7, 2025 00:15 | July 7, 2025 01:45 | 1h 30m | 1,974 | 2,959 |
| 8 | March 4, 2025 15:45 | March 4, 2025 18:30 | 2h 45m | 1,094 | 796 |
| 9 | March 14, 2025 19:45 | March 15, 2025 23:45 | 1d 4h | 984 | 5,665 |
| 10 | April 1, 2025 18:45 | April 1, 2025 20:15 | 1h 30m | 969 | 244 |
Outage episodes by size in 2025: 60 reached 100+ customers, 8 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 Williamson 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 |
|---|---|---|---|---|---|
| Ameren Illinois Company | 2024 | 3.7 hrs | 1.13 | 2.0 hrs | 0.91 |
| Egyptian Electric Coop Assn | 2024 | 2.1 hrs | - | - | - |
| Southeastern IL Elec Coop, Inc | 2024 | 10.0 hrs | 3.07 | 2.3 hrs | 1.50 |
| Ameren | - | - | - | - | - |
| Southern Illinois Elec Coop | - | - | - | - | - |
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 ÷ 35,624 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. Williamson County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), Williamson 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/williamson-county