Johnson County Power Outage History
2014–2025 · Illinois
Average — typical outage frequency and duration nationally. How grades are calculated
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Jun 29, 2018 | 14 hrs | 2,467 (35%) | Thunderstorm Wind |
| Aug 21, 2017 | 0 hrs | 2,409 (35%) | Dense Fog |
| May 27, 2024 | 47 hrs | 1,873 (27%) | Tornado |
| Apr 14, 2025 | 1 hrs | 1,424 (20%) | Unnamed event |
| Mar 15, 2025 | 17 hrs | 1,322 (19%) | Strong Wind |
Over the 12 years from 2014 to 2025, Johnson County recorded 361 distinct power outage events, averaging 2.6 hours per event.
The single worst outage on record in Johnson County started June 29, 2018 (Thunderstorm Wind), lasting 14 hours and leaving up to 2,467 customers without power (35% of the county) at its peak.
June has historically been the worst month for outages in Johnson County, with 47 events recorded during that month across the dataset.
Based on this history, Johnson County earns a Reliability Grade of C, placing it in the 53rd percentile nationally for grid reliability (higher percentile = more reliable).
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Similar counties in Illinois
Counties with the closest reliability grade and national percentile to Johnson County.
| County | Grade | National percentile |
|---|---|---|
| Hardin County | C | 53rd |
| Hancock County | C | 54th |
| Jasper County | C | 54th |
| Bond County | C | 52nd |
| Piatt County | C | 52nd |
FAQ
How often does power go out in Johnson County?
Between 2014 and 2025, Johnson County recorded 361 outage events, averaging 2.6 hours each.
What is Johnson County's reliability grade?
Johnson County has a Reliability Grade of C, in the 53rd national percentile.
What was the worst power outage in Johnson County?
The worst outage on record started June 29, 2018 (Thunderstorm Wind), lasting 14 hours and affecting up to 2,467 customers.