Hamilton CountyPower Outage History
What this grade means
Better than average — fewer or shorter outages than most counties. This county's outage history is better than the national median: recorded outages are less frequent and/or shorter in duration than a typical US county experienced over the same 12-year period. It isn't in the top tier nationally, but its track record points to lower-than-average outage risk.
Outages by year
Outages by month (seasonality)
Worst outage events on record
| Date | Duration | Customers affected | Cause |
|---|---|---|---|
| Dec 16, 2021 | 9 hrs | 1,621 (17%) | Tornado |
| Apr 3, 2020 | 1 hrs | 1,431 (15%) | Unnamed event |
| Dec 10, 2021 | 16 hrs | 1,317 (14%) | Unnamed event |
| Aug 10, 2020 | 15 hrs | 1,142 (12%) | Drought |
| Aug 10, 2020 | 6 hrs | 1,123 (12%) | Drought |
Was There an Outage on a Specific Date?
Pick a date to see whether a power outage was recorded for Hamilton County, Iowa that day.
Over the 11 years from 2015 to 2025, Hamilton County recorded 209 distinct power outage events, averaging 2.6 hours per event.
The single worst outage on record in Hamilton County started December 16, 2021 (Tornado), lasting 9 hours and leaving up to 1,621 customers without power (17% of the county) at its peak.
May has historically been the worst month for outages in Hamilton County, with 27 events recorded during that month across the dataset.
Based on this history, Hamilton County earns a Reliability Grade of B, placing it in the 80th percentile nationally for grid reliability (higher percentile = more reliable).
Similar counties in Iowa
Counties with the closest reliability grade and national percentile to Hamilton County.
| County | Grade | National percentile |
|---|---|---|
| Cerro Gordo County | A | 80th |
| Clarke County | A | 80th |
| Clayton County | A | 80th |
| Decatur County | B | 79th |
| O'Brien County | B | 79th |
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 Hamilton County?
Between 2015 and 2025, Hamilton County recorded 209 outage events, averaging 2.6 hours each.
What is Hamilton County's reliability grade?
Hamilton County has a Reliability Grade of B, in the 80th national percentile.
What was the worst power outage in Hamilton County?
The worst outage on record started December 16, 2021 (Tornado), lasting 9 hours and affecting up to 1,621 customers.