Big Horn County Power Outage History
2020–2025 · 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 |
|---|---|---|---|
| Apr 17, 2025 | 36 hrs | 1,779 (26%) | Winter Storm |
| Jun 11, 2022 | 10 hrs | 1,778 (26%) | Thunderstorm Wind |
| Jun 12, 2025 | 2 hrs | 304 (4%) | Unnamed event |
| Nov 30, 2023 | 7 hrs | 187 (3%) | Unnamed event |
| Nov 13, 2025 | 5 hrs | 129 (2%) | High Wind |
Over the 6 years from 2020 to 2025, Big Horn County recorded 43 distinct power outage events, averaging 6.9 hours per event.
The single worst outage on record in Big Horn County started April 17, 2025 (Winter Storm), lasting 36 hours and leaving up to 1,779 customers without power (26% of the county) at its peak.
July has historically been the worst month for outages in Big Horn County, with 9 events recorded during that month across the dataset.
Based on this history, Big Horn County earns a Reliability Grade of A, placing it in the 94th percentile nationally for grid reliability (higher percentile = more reliable).
Sized for Big Horn County's outage profile
See more picks in our Best Small Power Stations (Under 1,000Wh) roundup.
Outage-prep kit
See our outage-prep guides.
Similar counties in Montana
Counties with the closest reliability grade and national percentile to Big Horn County.
| County | Grade | National percentile |
|---|---|---|
| Fallon County | A | 94th |
| Roosevelt County | A | 94th |
| Dawson County | A | 93rd |
| Powder River County | A | 95th |
| Gallatin County | A | 92nd |
Most reliable counties in Montana
The top 3 counties in Montana by reliability grade and percentile.
| County | Grade | National percentile |
|---|---|---|
| Powder River County | A | 95th |
| Roosevelt County | A | 94th |
| Fallon County | A | 94th |
Least reliable counties in Montana
The bottom 3 counties in Montana by reliability grade and percentile.
| County | Grade | National percentile |
|---|---|---|
| Lincoln County | F | 14th |
| Sanders County | D | 20th |
| Madison County | D | 31st |
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 Big Horn County?
Between 2020 and 2025, Big Horn County recorded 43 outage events, averaging 6.9 hours each.
What is Big Horn County's reliability grade?
Big Horn County has a Reliability Grade of A, in the 94th national percentile.
What was the worst power outage in Big Horn County?
The worst outage on record started April 17, 2025 (Winter Storm), lasting 36 hours and affecting up to 1,779 customers.