Custer CountyPower Outage History
2016–2025 · South Dakota
Worse than average — more frequent or longer outages than most counties.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Dec 18, 2025 | 159 hrs | 5,295 (86%) | High Wind |
| Nov 13, 2025 | 7 hrs | 4,910 (80%) | Unnamed event |
| May 22, 2019 | 2 hrs | 1,649 (27%) | Heavy Snow |
| Mar 13, 2021 | 3 hrs | 1,564 (25%) | Heavy Snow |
| Nov 30, 2019 | 11 hrs | 1,506 (25%) | Blizzard |
Over the 10 years from 2016 to 2025, Custer County recorded 341 distinct power outage events, averaging 3.6 hours per event.
The single worst outage on record in Custer County started December 18, 2025 (High Wind), lasting 159 hours and leaving up to 5,295 customers without power (86% of the county) at its peak.
June has historically been the worst month for outages in Custer County, with 48 events recorded during that month across the dataset.
Based on this history, Custer County earns a Reliability Grade of D, placing it in the 30th percentile nationally for grid reliability (higher percentile = more reliable).
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Similar counties in South Dakota
Counties with the closest reliability grade and national percentile to Custer County.
| County | Grade | National percentile |
|---|---|---|
| Grant County | D | 31st |
| Perkins County | D | 29th |
| Marshall County | D | 37th |
| Harding County | D | 21st |
| McCook County | C | 43rd |
Most reliable counties in South Dakota
The top 3 counties in South Dakota by reliability grade and percentile.
| County | Grade | National percentile |
|---|---|---|
| Clay County | A | 100th |
| Codington County | A | 98th |
| Tripp County | A | 98th |
Least reliable counties in South Dakota
The bottom 3 counties in South Dakota by reliability grade and percentile.
| County | Grade | National percentile |
|---|---|---|
| Harding County | D | 21st |
| Perkins County | D | 29th |
| Custer County | D | 30th |
Most reliable counties nationally
The top 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | South Dakota | A | 100th |
| Clearwater County | Minnesota | A | 99th |
| Limestone County | Alabama | A | 99th |
Least reliable counties nationally
The bottom 3 counties nationally by reliability grade and percentile.
| County | State | Grade | National percentile |
|---|---|---|---|
| Clay County | West Virginia | F | 0th |
| Lincoln County | West Virginia | F | 0th |
| Cameron Parish | Louisiana | F | 0th |
FAQ
How often does power go out in Custer County?
Between 2016 and 2025, Custer County recorded 341 outage events, averaging 3.6 hours each.
What is Custer County's reliability grade?
Custer County has a Reliability Grade of D, in the 30th national percentile.
What was the worst power outage in Custer County?
The worst outage on record started December 18, 2025 (High Wind), lasting 159 hours and affecting up to 5,295 customers.