Power outage history
Williamson County Illinois
4.2hours
without power for the average customer in a typical year, 2018–2025
53rd most of 101 in Illinois 35% below the national median
Every day since 2015
Eleven years, one night at a time
Each cell is a day. The brighter it is, the larger the share of Williamson's customers who were without power at that day's worst moment.
Year by year
Hours in the dark, per customer
2025 was the worst well-recorded year, at 15 hours for the average customer. Hatched years have a thin record and are left out of the averages.
Williamson, hours without power per customer
The record
The biggest outages since 2015
Ranked by customer-hours lost: customers out multiplied by how long they stayed out. Times are local.
| Began | Storm | Peak out | Share | Lasted | 90% restored | Customer-hours |
|---|---|---|---|---|---|---|
| Jan 5, 2025 | Ice storm | 10,894 | 31% | 3.9 d | 2.5 d | 393k |
| Jun 28, 2018 | Tornadoes | 7,504 | 21% | 44 h | 34 h | 126k |
| May 26, 2024 | Thunderstorms | 8,670 | 24% | 36 h | 13 h | 69k |
| May 16, 2025 | Thunderstorms | 5,741 | 16% | 22 h | 21 h | 37k |
| Jan 30, 2019 | Winter storm | 6,468 | 18% | 7.8 h | 6.5 h | 27k |
| Jan 30, 2019 | Winter storm | 6,525 | 18% | 5.8 h | 5.2 h | 19k |
| Jul 5, 2024 | Heat | 4,810 | 14% | 7.8 h | 3.5 h | 17k |
| Jul 29, 2023 | Thunderstorms | 4,280 | 12% | 5.2 h | 3.5 h | 15k |
| Jul 10, 2021 | Thunderstorms | 6,630 | 19% | 5.2 h | 3.5 h | 15k |
| Jun 21, 2019 | Thunderstorms | 6,568 | 18% | 5.2 h | 2.8 h | 15k |
| Jun 1, 2021 | No storm report | 1,099 | 3% | 12 h | – | 13k |
| Mar 23, 2019 | No storm report | 7,719 | 22% | 1.8 h | 30 min | 12k |
| May 11, 2016 | Thunderstorms | 5,019 | 14% | 4.8 h | 4.5 h | 11k |
| Apr 2, 2024 | Tornadoes | 1,738 | 5% | 9.5 h | – | 11k |
| Jan 10, 2025 | Winter storm | 4,603 | 13% | 2.5 h | 2.2 h | 9.4k |
| Apr 21, 2016 | No storm report | 2,949 | 8% | 4.2 h | 3.8 h | 9.4k |
| Mar 23, 2023 | Thunderstorms | 1,288 | 4% | 7.0 h | – | 8.1k |
| Apr 26, 2017 | No storm report | 4,647 | 13% | 1.8 h | 12 min | 8.1k |
| May 7, 2023 | Thunderstorms | 2,928 | 8% | 3.8 h | 3.8 h | 8.0k |
| Jan 16, 2017 | No storm report | 1,783 | 5% | 8.8 h | 11 h | 7.8k |
| Jun 26, 2015 | No storm report | 5,033 | 14% | 2.8 h | 2.5 h | 6.2k |
| Jul 20, 2020 | Heat | 2,263 | 6% | 4.2 h | 2.5 h | 5.5k |
| Sep 22, 2016 | No storm report | 3,649 | 10% | 1.5 h | 1.5 h | 5.5k |
| May 9, 2022 | No storm report | 3,387 | 10% | 2.2 h | 1.2 h | 5.2k |
| Nov 28, 2018 | No storm report | 1,496 | 4% | 5.5 h | – | 5.1k |
| Mar 15, 2025 | Windstorm | 984 | 3% | 7.2 h | – | 5.1k |
| Jan 10, 2025 | Winter storm | 3,459 | 10% | 1.5 h | 1.2 h | 5.0k |
| Mar 11, 2022 | Winter storm | 1,547 | 4% | 3.8 h | – | 4.9k |
| Apr 3, 2018 | Tornadoes | 1,680 | 5% | 5.2 h | – | 4.7k |
| Jun 25, 2024 | Heat | 2,832 | 8% | 1.8 h | 1.5 h | 4.7k |
After the peak
How fast the lights come back
Each line is one major outage, from its peak. The amber line is the typical path.
When it happens
The outage clock
Customer-hours out by month (rings, January innermost) and local hour, 2018–2025.
What was happening
Weather behind the outages
Each outage is matched to NOAA storm reports for Williamson from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.
- Ice storm 40%
- Thunderstorms 19%
- Tornadoes 15%
- No storm on record 14%
- Winter storm 7.5%
- Heat 3.0%
- Windstorm 1.8%
Who keeps the lights on
Utilities serving Williamson
As each utility reports to the Energy Information Administration for its whole Illinois territory, not this county alone. Outage minutes include major storm days.
| Utility | Type | Outage min / yr | Excl. major storms | Outages / yr | Residential ¢/kWh | Customers |
|---|---|---|---|---|---|---|
| Ameren Illinois Company | Investor Owned | 287 | 130 | 1.19 | 16.7 | 1.1M |
| Southern Illinois Elec Coop | IL | 228 | 105 | – | 15.3 | 152k |
| Southeastern IL Elec Coop, Inc | Cooperative | 2,214 | 172 | 3.95 | 14.8 | 23k |
| Egyptian Electric Coop Assn | Cooperative | 773 | 24 | 4.62 | 16.2 | 14k |
EIA Form 861, latest year each utility reported. Outage minutes are SAIDI, the yearly minutes the average customer goes without power; outages a year are SAIFI.
About these numbers
Notes
Outages come from the EAGLE-I record of utility outage maps collected every 15 minutes by Oak Ridge National Laboratory. Hours without power are customer-hours divided by the county's 35,624 electricity customers. Averages use well-covered years from 2018. Outages shorter than 15 minutes, and utilities that publish no outage map, are not in the record, so these figures understate the total. How every number is made →