Power outage history
Pennington County South Dakota
3.4hours
without power for the average customer in a typical year, 2018–2025
24th most of 32 in South Dakota 48% 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 Pennington'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 13 hours for the average customer. Hatched years have a thin record and are left out of the averages.
Pennington, 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 |
|---|---|---|---|---|---|---|
| Dec 18, 2025 | Windstorm | 25,159 | 37% | 4.7 d | 2.6 d | 552k |
| Sep 3, 2021 | No storm report | 1,321 | 2% | 3.9 d | – | 120k |
| Nov 13, 2025 | No storm report | 27,852 | 41% | 7.0 h | 4.2 h | 105k |
| Mar 25, 2025 | No storm report | 1,700 | 3% | 27 h | – | 46k |
| Nov 30, 2019 | Winter storm | 4,701 | 7% | 11 h | 5.2 h | 34k |
| Oct 30, 2023 | No storm report | 1,287 | 2% | 20 h | – | 25k |
| Mar 27, 2019 | No storm report | 1,585 | 2% | 16 h | – | 25k |
| Feb 24, 2025 | Windstorm | 1,303 | 2% | 22 h | – | 16k |
| Dec 26, 2023 | Winter storm | 1,579 | 2% | 6.2 h | – | 9.8k |
| Mar 13, 2021 | No storm report | 3,084 | 5% | 3.2 h | – | 8.4k |
| Dec 11, 2019 | No storm report | 3,841 | 6% | 4.2 h | 3.8 h | 8.2k |
| Dec 17, 2025 | No storm report | 1,810 | 3% | 4.5 h | – | 7.3k |
| May 22, 2019 | Winter storm | 1,067 | 2% | 11 h | – | 6.3k |
| Jun 28, 2023 | Thunderstorms | 1,917 | 3% | 2.8 h | – | 5.3k |
| Oct 7, 2018 | No storm report | 4,021 | 6% | 1.2 h | 12 h | 5.0k |
| May 22, 2018 | Thunderstorms | 4,963 | 7% | 1.0 h | 1.5 h | 5.0k |
| Jun 22, 2025 | No storm report | 1,043 | 2% | 4.8 h | – | 5.0k |
| Sep 24, 2018 | No storm report | 1,672 | 2% | 2.8 h | – | 4.5k |
| Oct 13, 2021 | Winter storm | 779 | 1% | 6.5 h | – | 4.4k |
| Jun 20, 2020 | No storm report | 5,384 | 8% | 1.5 h | 1.5 h | 4.4k |
| Feb 11, 2021 | No storm report | 2,912 | 4% | 1.5 h | – | 4.1k |
| Jun 15, 2025 | Thunderstorms | 851 | 1% | 4.8 h | – | 3.7k |
| May 14, 2020 | No storm report | 1,532 | 2% | 3.0 h | – | 3.7k |
| Feb 19, 2016 | Windstorm | 4,872 | 7% | 1.0 h | 1.0 h | 3.6k |
| May 22, 2019 | Winter storm | 875 | 1% | 4.5 h | – | 3.5k |
| Apr 6, 2021 | Winter storm | 2,103 | 3% | 2.0 h | – | 3.5k |
| Sep 4, 2023 | Thunderstorms | 1,614 | 2% | 2.0 h | – | 3.2k |
| May 13, 2017 | No storm report | 1,658 | 2% | 1.8 h | – | 2.9k |
| Apr 6, 2024 | Winter storm | 1,760 | 3% | 1.8 h | – | 2.9k |
| May 12, 2019 | No storm report | 927 | 1% | 3.0 h | – | 2.8k |
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 Pennington from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.
- Windstorm 52%
- No storm on record 39%
- Winter storm 6.7%
- Thunderstorms 2.1%
Who keeps the lights on
Utilities serving Pennington
As each utility reports to the Energy Information Administration for its whole South Dakota territory, not this county alone. Outage minutes include major storm days.
| Utility | Type | Outage min / yr | Excl. major storms | Outages / yr | Residential ¢/kWh | Customers |
|---|---|---|---|---|---|---|
| Black Hills Power, Inc. | Investor Owned | 541 | 43 | 2.27 | 15.1 | 68k |
| West River Electric Assn Inc | Cooperative | 24 | 24 | 0.30 | 15.2 | 19k |
| Black Hills Electric Coop, Inc | Cooperative | 2,487 | 120 | 3.41 | 14.8 | 9.4k |
| WAPA-- Western Area Power Administration | Federal | – | – | – | – | – |
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
- Haakon 12 h
- Custer 11 h
- Weston, WY 6.8 h
- Jackson 5.1 h
- Lawrence 3.9 h
- Pennington (this county) 3.4 h
- Meade 3.4 h
- Oglala Lakota 1.0 h
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 68,130 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 →