County annual report · FIPS 30063
2021 Missoula County, MT Power Outage Report
In 2021, customers in Missoula County, MT went without power for an average of 1.9 hours, a total of 112K customer-hours (Montana average 5.0 hours). That ranks 35th worst of 51 Montana counties and 2240th of 2,974 nationally.
Compared with MT, the US and 2020
Coverage line is EAGLE-I's share of Montana customers tracked each year.
Biggest outages in Missoula 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 2, 2021 02:30 | August 2, 2021 07:00 | 4h 30m | 6,378 | 21K |
| 2 | November 16, 2021 00:15 | November 17, 2021 02:00 | 1d 1h | 3,684 | 26K |
| 3 | December 23, 2021 23:00 | December 24, 2021 03:45 | 4h 45m | 2,010 | 2,902 |
| 4 | July 2, 2021 00:00 | July 2, 2021 11:45 | 11h 45m | 1,911 | 6,684 |
| 5 | August 31, 2021 20:45 | August 31, 2021 21:30 | 45m | 1,906 | 953 |
| 6 | September 23, 2021 16:45 | September 23, 2021 18:00 | 1h 15m | 1,852 | 2,313 |
| 7 | September 22, 2021 15:45 | September 22, 2021 17:15 | 1h 30m | 1,851 | 2,313 |
| 8 | January 13, 2021 15:15 | January 15, 2021 15:15 | 2d | 1,833 | 6,716 |
| 9 | June 14, 2021 02:15 | June 14, 2021 07:00 | 4h 45m | 1,534 | 4,561 |
| 10 | April 23, 2021 22:15 | April 24, 2021 04:15 | 6h | 1,456 | 3,255 |
Outage episodes by size in 2021: 43 reached 100+ customers, 11 reached 1,000+ customers, 0 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 Missoula 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 |
|---|---|---|---|---|---|
| NorthWestern Energy LLC - (MT) | 2021 | 2.5 hrs | 1.37 | 2.1 hrs | 1.18 |
| Missoula Electric Coop, Inc | 2021 | 12.7 hrs | 3.21 | 6.5 hrs | 2.76 |
| Ravalli County Elec Coop, Inc | 2018 | 4.2 hrs | 1.53 | 2.5 hrs | 1.41 |
| Bonneville Power Administration | - | - | - | - | - |
| NorthWestern Energy | - | - | - | - | - |
| USBIA-Mission Valley Power | - | - | - | - | - |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about 76% of Montana's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 57,348 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. Missoula County has data for 2019–2025.
Cite this report
MassOutage (massoutage.com), Missoula County, MT 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/montana/missoula-county