County annual report · FIPS 55133
2021 Waukesha County, WI Power Outage Report
In 2021, customers in Waukesha County, WI went without power for an average of 12.9 hours, a total of 1.9M customer-hours (Wisconsin average 4.7 hours). That ranks 8th worst of 72 Wisconsin counties and 641st of 2,974 nationally.
Compared with WI, the US and 2020
Coverage line is EAGLE-I's share of Wisconsin customers tracked each year.
Biggest outages in Waukesha County, 2021
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | August 11, 2021 00:00 | August 11, 2021 12:45 | 12h 45m | 45,425 | 320K |
| 2 | August 11, 2021 13:30 | August 11, 2021 14:45 | 1h 15m | 29,851 | 35K |
| 3 | August 11, 2021 18:15 | August 17, 2021 03:00 | 5d 8h | 29,256 | 630K |
| 4 | August 11, 2021 15:30 | August 11, 2021 17:15 | 1h 45m | 25,987 | 38K |
| 5 | December 15, 2021 23:30 | December 19, 2021 18:15 | 3d 18h | 18,027 | 296K |
| 6 | July 29, 2021 06:00 | July 31, 2021 02:15 | 1d 20h | 15,378 | 170K |
| 7 | July 15, 2021 05:30 | July 16, 2021 05:00 | 23h 30m | 3,885 | 20K |
| 8 | September 30, 2021 21:15 | October 1, 2021 02:00 | 4h 45m | 3,859 | 8,546 |
| 9 | May 26, 2021 06:30 | May 26, 2021 09:00 | 2h 30m | 3,721 | 6,530 |
| 10 | June 29, 2021 13:00 | June 29, 2021 23:00 | 10h | 3,459 | 8,174 |
Outage episodes by size in 2021: 129 reached 100+ customers, 56 reached 1,000+ customers, 6 reached 10,000+ customers.
Utility reliability filed with the EIA
SAIDI (average outage time per customer) and SAIFI (average interruptions per customer) that utilities serving Waukesha County reported on EIA Form 861 for 2021, or their most recent earlier filing. Utility-wide figures, not county-specific.
| Utility | EIA year | SAIDI | SAIFI | SAIDI excl. major events | SAIFI excl. major events |
|---|---|---|---|---|---|
| Wisconsin Electric Power Co | 2021 | 7.0 hrs | 1.13 | 1.7 hrs | 0.73 |
| Oconomowoc Utilities | - | - | - | - | - |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about 85% of Wisconsin's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 143,177 customers (ORNL modeled county customer count), including major storm days. It is comparable across counties but is not the SAIDI a utility files.
- An outage event is a continuous stretch with customers out; counts at 100, 1,000 and 10,000+ use its peak.
- Years loaded: 2015–2025. Waukesha County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), Waukesha County, WI annual power outage report, 2021, data as of Oct 3, 2026 02:41 UTC, sources: DOE EAGLE-I (https://eagle-i.doe.gov/); EAGLE-I modeled customer counts (MCC) (https://figshare.com/); EIA Form 861 (utility reliability) (https://www.eia.gov/electricity/data/eia861/). https://massoutage.com/reports/2021/wisconsin/waukesha-county