Cass County Power Outage History
2015–2025 · Iowa
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 |
|---|---|---|---|
| Dec 15, 2021 | 11 hrs | 1,135 (11%) | Tornado |
| Sep 17, 2019 | 1 hrs | 1,093 (11%) | Unnamed event |
| Mar 19, 2025 | 0 hrs | 1,058 (10%) | Thunderstorm Wind |
| Apr 1, 2023 | 0 hrs | 1,057 (10%) | Unnamed event |
| Jan 9, 2024 | 4 hrs | 993 (10%) | Drought |
Over the 11 years from 2015 to 2025, Cass County recorded 174 distinct power outage events, averaging 2.5 hours per event.
The single worst outage on record in Cass County started December 15, 2021 (Tornado), lasting 11 hours and leaving up to 1,135 customers without power (11% of the county) at its peak.
May has historically been the worst month for outages in Cass County, with 27 events recorded during that month across the dataset.
Based on this history, Cass County earns a Reliability Grade of A, placing it in the 89th percentile nationally for grid reliability (higher percentile = more reliable).
Sized for Cass County's outage profile
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Similar counties in Iowa
Counties with the closest reliability grade and national percentile to Cass County.
| County | Grade | National percentile |
|---|---|---|
| Marion County | A | 89th |
| Adair County | A | 90th |
| Carroll County | A | 88th |
| Black Hawk County | A | 88th |
| Osceola County | A | 88th |
FAQ
How often does power go out in Cass County?
Between 2015 and 2025, Cass County recorded 174 outage events, averaging 2.5 hours each.
What is Cass County's reliability grade?
Cass County has a Reliability Grade of A, in the 89th national percentile.
What was the worst power outage in Cass County?
The worst outage on record started December 15, 2021 (Tornado), lasting 11 hours and affecting up to 1,135 customers.