Sumter CountyPower Outage History
What this grade means
Average — typical outage frequency and duration nationally. This county sits in the middle of the national distribution — its outage frequency and duration over the past 12 years are close to the nationwide median, neither notably better nor worse than most other US counties. A typical amount of backup-power preparedness is reasonable here.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Oct 8, 2016 | 12 hrs | 27,446 (31%) | Hurricane Matthew |
| Oct 8, 2016 | 120 hrs | 26,512 (30%) | Hurricane Matthew |
| Jun 20, 2025 | <1 hr | 22,428 (26%) | Heavy Rain |
| Apr 8, 2021 | 6 hrs | 15,457 (18%) | Unnamed event |
| Jul 13, 2019 | 3 hrs | 14,520 (17%) | Unnamed event |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Sumter County, South Carolina that day.
Over the 12 years from 2014 to 2025, Sumter County recorded 775 distinct power outage events, averaging 2.5 hours per event.
The single worst outage on record in Sumter County started October 8, 2016 (Hurricane Matthew), lasting 12 hours and leaving up to 27,446 customers without power (31% of the county) at its peak.
August has historically been the worst month for outages in Sumter County, with 113 events recorded during that month across the dataset.
Based on this history, Sumter County earns a Reliability Grade of C, placing it in the 56th percentile nationally for grid reliability (higher percentile = more reliable).
Similar counties in South Carolina
Counties with the closest reliability grade and national percentile to Sumter County.
| County | Grade | National percentile |
|---|---|---|
| Marlboro County | C | 55th |
| Jasper County | C | 54th |
| Clarendon County | C | 58th |
| Williamsburg County | C | 52nd |
| Calhoun County | B | 60th |
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 Sumter County?
Between 2014 and 2025, Sumter County recorded 775 outage events, averaging 2.5 hours each.
What is Sumter County's reliability grade?
Sumter County has a Reliability Grade of C, in the 56th national percentile.
What was the worst power outage in Sumter County?
The worst outage on record started October 8, 2016 (Hurricane Matthew), lasting 12 hours and affecting up to 27,446 customers.