Sierra CountyPower Outage History
What this grade means
(How grades are calculated)Bottom 20% least reliable nationally — frequent and/or long outages. This county ranks in the least reliable fifth of all US counties in our dataset: some combination of frequent outages, long restoration times, or customers affected puts it near the bottom nationally. Backup power is worth prioritizing here rather than treating it as optional.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Feb 28, 2023 | 133 hrs | 4,203 (77%) | Winter Storm |
| Mar 5, 2023 | 56 hrs | 3,988 (73%) | Blizzard |
| Mar 2, 2024 | 145 hrs | 2,454 (45%) | Blizzard |
| Mar 15, 2020 | 16 hrs | 1,701 (31%) | Heavy Snow |
| Nov 23, 2024 | 40 hrs | 1,682 (31%) | Heavy Snow |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Sierra County, California that day.
Over the 8 years from 2018 to 2025, Sierra County recorded 818 distinct power outage events, averaging 7.5 hours per event.
The single worst outage on record in Sierra County started February 28, 2023 (Winter Storm), lasting 133 hours and leaving up to 4,203 customers without power (77% of the county) at its peak.
October has historically been the worst month for outages in Sierra County, with 174 events recorded during that month across the dataset.
Based on this history, Sierra County earns a Reliability Grade of F, placing it in the 0th percentile nationally for grid reliability (higher percentile = more reliable).
Similar counties in California
Counties with the closest reliability grade and national percentile to Sierra County.
| County | Grade | National percentile |
|---|---|---|
| Plumas County | F | 1st |
| Mariposa County | F | 1st |
| Calaveras County | F | 1st |
| Amador County | F | 1st |
| Tuolumne County | F | 1st |
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 Sierra County?
Between 2018 and 2025, Sierra County recorded 818 outage events, averaging 7.5 hours each.
What is Sierra County's reliability grade?
Sierra County has a Reliability Grade of F, in the 0th national percentile.
What was the worst power outage in Sierra County?
The worst outage on record started February 28, 2023 (Winter Storm), lasting 133 hours and affecting up to 4,203 customers.