Tuolumne CountyPower Outage History
What this grade means
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 |
|---|---|---|---|
| Oct 10, 2019 | <1 hr | 37,533 (99%) | Strong Wind |
| Sep 9, 2023 | 54 hrs | 37,050 (98%) | Wildfire |
| Aug 26, 2021 | 29 hrs | 37,001 (98%) | Drought |
| Oct 10, 2019 | <1 hr | 36,209 (96%) | Strong Wind |
| Oct 9, 2019 | 2 hrs | 35,846 (95%) | Strong Wind |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Tuolumne County, California that day.
Over the 8 years from 2018 to 2025, Tuolumne County recorded 1,118 distinct power outage events, averaging 4.3 hours per event.
The single worst outage on record in Tuolumne County started October 10, 2019 (Strong Wind), lasting less than 1 hour and leaving up to 37,533 customers without power (99% of the county) at its peak.
October has historically been the worst month for outages in Tuolumne County, with 144 events recorded during that month across the dataset.
Based on this history, Tuolumne County earns a Reliability Grade of F, placing it in the 1st percentile nationally for grid reliability (higher percentile = more reliable).
Similar counties in California
Counties with the closest reliability grade and national percentile to Tuolumne County.
| County | Grade | National percentile |
|---|---|---|
| Amador County | F | 1st |
| Butte County | F | 1st |
| Calaveras County | F | 1st |
| Mariposa County | F | 1st |
| Plumas 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 Tuolumne County?
Between 2018 and 2025, Tuolumne County recorded 1,118 outage events, averaging 4.3 hours each.
What is Tuolumne County's reliability grade?
Tuolumne County has a Reliability Grade of F, in the 1st national percentile.
What was the worst power outage in Tuolumne County?
The worst outage on record started October 10, 2019 (Strong Wind), lasting less than 1 hour and affecting up to 37,533 customers.