Custer County Power Outage History
2017–2025 · Montana
Top 20% most reliable nationally — infrequent, short outages. How grades are calculated
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Dec 3, 2020 | 1 hrs | 4,487 (64%) | Unnamed event |
| Nov 7, 2017 | 0 hrs | 4,342 (62%) | Unnamed event |
| Apr 13, 2017 | 1 hrs | 4,145 (59%) | Unnamed event |
| Oct 2, 2022 | 1 hrs | 4,016 (57%) | Unnamed event |
| Oct 2, 2022 | 1 hrs | 3,063 (44%) | Unnamed event |
Over the 9 years from 2017 to 2025, Custer County recorded 128 distinct power outage events, averaging 1.4 hours per event.
The single worst outage on record in Custer County started December 3, 2020, lasting 1 hours and leaving up to 4,487 customers without power (64% of the county) at its peak.
July has historically been the worst month for outages in Custer County, with 27 events recorded during that month across the dataset.
Based on this history, Custer County earns a Reliability Grade of A, placing it in the 87th percentile nationally for grid reliability (higher percentile = more reliable).
Sized for Custer County's outage profile
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Similar counties in Montana
Counties with the closest reliability grade and national percentile to Custer County.
| County | Grade | National percentile |
|---|---|---|
| Yellowstone County | A | 89th |
| Silver Bow County | A | 89th |
| Stillwater County | A | 90th |
| Beaverhead County | A | 84th |
| Deer Lodge County | A | 83rd |
FAQ
How often does power go out in Custer County?
Between 2017 and 2025, Custer County recorded 128 outage events, averaging 1.4 hours each.
What is Custer County's reliability grade?
Custer County has a Reliability Grade of A, in the 87th national percentile.
What was the worst power outage in Custer County?
The worst outage on record started December 3, 2020, lasting 1 hours and affecting up to 4,487 customers.