Power Out Map
– 0% of Valley out 0 customers out in Montana

Power outage history

Valley County Montana

7.3hours

without power for the average customer in a typical year, 2018–2025

14th most of 35 in Montana close to the national median

Worst outage on record Nov 4, 2021 81% of customers out · 90% back in 6.8 hours
Hours without power, average customer per year 7.3h / yr State average 4.9 h · national median 6.6 h
Major outages a year 5.8 Peaks over 10% of customers or 50,000 customers
Typical time to restore 90% 2hours Median across major outages, from the peak
Longest single outage 2.2days Dec 17, 2025, over 1% of customers out
Outage hours on storm days 39% Share falling on days with a NOAA storm report here
Worst year 2021 16 hours without power, average customer
Electricity customers 3,912 ORNL customer model · 6 well-covered years

Every day since 2015

Eleven years, one night at a time

Each cell is a day. The brighter it is, the larger the share of Valley's customers who were without power at that day's worst moment.

20152016201720182019202020212022202320242025
0%100% of customers out

Year by year

Hours in the dark, per customer

2021 was the worst well-recorded year, at 16 hours for the average customer. Hatched years have a thin record and are left out of the averages.

Valley, hours without power per customer

ValleyUS median countyMontana average
0 5 10 15 20 ’19 5.6 ’20 16 ’21 2.1 ’22 1.6 ’23 4.8 ’24 14 ’25 US 6.6 MT 4.9

The record

The biggest outages since 2015

Ranked by customer-hours lost: customers out multiplied by how long they stayed out. Times are local.

Began Storm Peak out Share Lasted 90% restored Customer-hours
Nov 4, 2021 No storm report 3,174 81% 7.0 h 6.8 h 21k
Dec 17, 2025 Winter storm 800 20% 2.2 d 2.0 h 12k
Jul 22, 2021 Thunderstorms 3,217 82% 4.0 h 1.0 h 8.6k
Jan 14, 2021 Windstorm 1,256 32% 20 h 19 h 8.6k
Dec 23, 2025 No storm report 2,687 69% 3.0 h 3.0 h 8.1k
Dec 26, 2025 No storm report 3,145 80% 3.0 h 2.8 h 5.6k
Jul 31, 2025 No storm report 2,373 61% 3.2 h 2.8 h 5.5k
May 20, 2020 Thunderstorms 628 16% 8.5 h 15 h 4.7k
Mar 31, 2024 No storm report 1,162 30% 3.8 h 2.8 h 4.2k
Mar 8, 2021 No storm report 2,890 74% 1.5 h 30 min 4.0k
Apr 5, 2022 Windstorm 1,545 39% 11 h 1.0 h 4.0k
Jan 24, 2025 No storm report 3,214 82% 1.5 h 1.2 h 3.8k

After the peak

How fast the lights come back

Each line is one major outage, from its peak. The amber line is the typical path.

0% 25% 50% 75% 100% peak+24h+48h+72h+96h half back by +2h 90% by +4h

When it happens

The outage clock

Customer-hours out by month (rings, January innermost) and local hour, 2018–2025.

00061218 Jan inside

What was happening

Weather behind the outages

Each outage is matched to NOAA storm reports for Valley from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.

  • No storm on record 61%
  • Thunderstorms 18%
  • Windstorm 12%
  • Winter storm 8.5%

Who keeps the lights on

Utilities serving Valley

As each utility reports to the Energy Information Administration for its whole Montana territory, not this county alone. Outage minutes include major storm days.

Utility Type Outage min / yr Excl. major storms Outages / yr Residential ¢/kWh Customers
NorthWestern Energy LLC Investor Owned 125 117 1.10 14.4 334k
NorVal Electric Cooperative, Inc MT – – – – 28k
Big Flat Electric Coop Inc MT – – – – 21k
WAPA-- Western Area Power Administration Federal – – – – –

EIA Form 861, latest year each utility reported. Outage minutes are SAIDI, the yearly minutes the average customer goes without power; outages a year are SAIFI.

Next door

Neighbouring counties

  • Phillips 11 h
  • Valley (this county) 7.3 h

Across Montana

Where it is darkest

Hours / yr64+

All Montana counties →

About these numbers

Notes

Outages come from the EAGLE-I record of utility outage maps collected every 15 minutes by Oak Ridge National Laboratory. Hours without power are customer-hours divided by the county's 3,912 electricity customers. Averages use well-covered years from 2018. Outages shorter than 15 minutes, and utilities that publish no outage map, are not in the record, so these figures understate the total. How every number is made →