Power outage history
Johnson County Iowa
5.5hours
without power for the average customer in a typical year, 2018–2025
25th most of 98 in Iowa 16% 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 Johnson's customers who were without power at that day's worst moment.
Year by year
Hours in the dark, per customer
2020 was the worst well-recorded year, at 31 hours for the average customer. Hatched years have a thin record and are left out of the averages.
Johnson, 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 |
|---|---|---|---|---|---|---|
| Aug 10, 2020 | Thunderstorms | 51,777 | 67% | 6.1 d | 4.0 d | 2.3M |
| Mar 31, 2023 | Tornadoes | 5,174 | 7% | 14 h | 13 h | 33k |
| May 7, 2023 | Thunderstorms | 6,587 | 8% | 7.2 h | 6.2 h | 27k |
| Jun 4, 2015 | No storm report | 4,054 | 5% | 12 h | 11 h | 22k |
| Jul 6, 2016 | Thunderstorms | 6,879 | 9% | 8.5 h | 8.0 h | 20k |
| Dec 1, 2025 | No storm report | 8,629 | 11% | 2.8 h | 2.8 h | 15k |
| Dec 14, 2024 | Ice storm | 2,608 | 3% | 8.8 h | – | 14k |
| Jan 10, 2020 | Winter storm | 2,195 | 3% | 14 h | – | 13k |
| Jun 18, 2023 | No storm report | 2,169 | 3% | 12 h | – | 12k |
| Jul 9, 2018 | No storm report | 1,195 | 2% | 9.5 h | – | 11k |
| Jan 30, 2021 | Winter storm | 5,738 | 7% | 2.5 h | 1.5 h | 11k |
| Jul 15, 2024 | Thunderstorms | 2,897 | 4% | 4.5 h | – | 10k |
| Jun 22, 2016 | Thunderstorms | 2,602 | 3% | 5.2 h | – | 9.7k |
| Oct 11, 2016 | No storm report | 12,594 | 16% | 1.5 h | 1.5 h | 9.4k |
| Jul 11, 2017 | Thunderstorms | 5,678 | 7% | 2.2 h | 2.0 h | 8.1k |
| Nov 30, 2025 | No storm report | 8,208 | 11% | 2.2 h | 12 min | 8.1k |
| Jul 9, 2017 | No storm report | 18,167 | 23% | 1.2 h | 1.0 h | 8.1k |
| Apr 16, 2024 | Thunderstorms | 1,969 | 3% | 4.0 h | – | 7.6k |
| Jun 9, 2018 | Thunderstorms | 10,998 | 14% | 1.0 h | 48 min | 7.6k |
| Aug 29, 2017 | No storm report | 2,559 | 3% | 3.2 h | – | 7.4k |
| Sep 13, 2020 | No storm report | 1,436 | 2% | 6.8 h | – | 7.3k |
| Aug 15, 2025 | Thunderstorms | 2,884 | 4% | 3.2 h | – | 7.1k |
| Aug 12, 2018 | No storm report | 3,258 | 4% | 3.2 h | – | 7.1k |
| Jun 12, 2022 | No storm report | 1,192 | 2% | 6.2 h | – | 7.0k |
| Jun 10, 2018 | No storm report | 1,118 | 1% | 6.8 h | – | 6.6k |
| Aug 12, 2025 | No storm report | 3,588 | 5% | 2.8 h | – | 6.4k |
| Jan 22, 2022 | No storm report | 3,357 | 4% | 2.0 h | – | 6.3k |
| Sep 6, 2020 | No storm report | 1,102 | 1% | 6.5 h | – | 6.3k |
| Feb 8, 2019 | Ice storm | 1,403 | 2% | 6.5 h | – | 6.2k |
| Sep 20, 2022 | No storm report | 3,534 | 5% | 1.8 h | – | 6.0k |
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 Johnson from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.
- Thunderstorms 83%
- No storm on record 13%
- Tornadoes 1.3%
- Winter storm 1.2%
- Ice storm 0.7%
Who keeps the lights on
Utilities serving Johnson
As each utility reports to the Energy Information Administration for its whole Iowa territory, not this county alone. Outage minutes include major storm days.
| Utility | Type | Outage min / yr | Excl. major storms | Outages / yr | Residential ¢/kWh | Customers |
|---|---|---|---|---|---|---|
| MidAmerican Energy Co | Investor Owned | 205 | 82 | 1.19 | 11.2 | 640k |
| Interstate Power and Light Co | Investor Owned | 89 | 74 | 0.82 | 17.8 | 419k |
| T I P Rural Electric Coop | IA | 156 | 156 | 1.33 | 11.9 | 82k |
| Corridor Energy Cooperative | Cooperative | 135 | 135 | 1.77 | 14.2 | 31k |
| Eastern Iowa Light & Power Coop | Cooperative | 92 | 79 | 0.93 | 14.8 | 20k |
| Farmers Electric Coop | IA | 87 | 51 | 1.03 | 12.3 | 12k |
| East-Central Iowa Rural Elec Coop | Cooperative | 67 | 67 | 0.88 | 13.1 | 7.4k |
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.
Next door
Neighbouring counties
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 77,769 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 →