County annual report · FIPS 30111
2020 Yellowstone County, MT Power Outage Report
In 2020, customers in Yellowstone County, MT went without power for an average of 2.5 hours, a total of 197K customer-hours (Montana average 5.6 hours). That ranks 39th worst of 50 Montana counties and 2038th of 3,019 nationally.
Compared with MT, the US and 2019
Coverage line is EAGLE-I's share of Montana customers tracked each year.
Biggest outages in Yellowstone County, 2020
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | April 28, 2020 14:15 | April 28, 2020 19:00 | 4h 45m | 5,853 | 8,109 |
| 2 | August 11, 2020 18:15 | August 12, 2020 01:15 | 7h | 4,537 | 9,093 |
| 3 | May 7, 2020 13:30 | May 7, 2020 23:15 | 9h 45m | 3,331 | 9,199 |
| 4 | December 9, 2020 16:00 | December 9, 2020 21:45 | 5h 45m | 3,284 | 7,964 |
| 5 | June 30, 2020 14:15 | July 1, 2020 12:00 | 21h 45m | 3,118 | 35K |
| 6 | July 7, 2020 16:15 | July 15, 2020 17:45 | 8d 1h | 3,022 | 17K |
| 7 | July 18, 2020 11:15 | July 18, 2020 21:15 | 10h | 2,423 | 14K |
| 8 | June 18, 2020 06:15 | June 18, 2020 15:30 | 9h 15m | 2,279 | 7,219 |
| 9 | June 7, 2020 12:15 | June 11, 2020 02:15 | 3d 14h | 1,643 | 12K |
| 10 | April 23, 2020 14:15 | April 23, 2020 15:15 | 1h | 1,241 | 621 |
Outage episodes by size in 2020: 70 reached 100+ customers, 12 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 Yellowstone County reported on EIA Form 861 for 2020, 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) | 2020 | 2.8 hrs | 1.13 | 2.0 hrs | 1.02 |
| Mid-Yellowstone Elec Coop, Inc | 2018 | 4.5 hrs | 3.82 | 4.5 hrs | 3.82 |
| WAPA-- Western Area Power Administration | - | - | - | - | - |
| NorthWestern Energy | - | - | - | - | - |
| Fergus Electric Coop, Inc | - | - | - | - | - |
| Yellowstone Valley Elec Co-op | - | - | - | - | - |
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 2020; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 77,606 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. Yellowstone County has data for 2019–2025.
Cite this report
MassOutage (massoutage.com), Yellowstone County, MT annual power outage report, 2020, 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/2020/montana/yellowstone-county