Power Out Map
– 0% of Custer out 0 customers out in South Dakota

Power outage history

Custer County South Dakota

11hours

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

7th most of 32 in South Dakota 1.7× the national median

Worst outage on record Dec 18, 2025 100% of customers out · 90% back in 4.3 days
Hours without power, average customer per year 11h / yr State average 4.8 h · national median 6.6 h
Major outages a year 3.6 Peaks over 10% of customers or 50,000 customers
Typical time to restore 90% 3hours Median across major outages, from the peak
Longest single outage 5.8days Dec 18, 2025, over 1% of customers out
Outage hours on storm days 85% Share falling on days with a NOAA storm report here
Worst year 2025 2.7 days without power, average customer
Electricity customers 4,481 ORNL customer model · 8 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 Custer'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

2025 was the worst well-recorded year, at 2.7 days for the average customer. Hatched years have a thin record and are left out of the averages.

Custer, hours without power per customer

CusterUS median countySouth Dakota average
0 5 10 15 20 1.4 ’16 ’17 0.2 ’18 5.2 ’19 5.5 ’20 6.1 ’21 3.4 ’22 3.5 ’23 2.2 ’24 65 ’25 US 6.6 SD 4.8

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
Dec 18, 2025 Windstorm 4,481 100% 5.8 d 4.3 d 251k
Nov 13, 2025 No storm report 4,481 100% 7.0 h 4.2 h 15k
Nov 30, 2019 Winter storm 1,506 34% 11 h 18 h 14k
Aug 12, 2023 Thunderstorms 1,386 31% 10 h 6.2 h 9.2k
Apr 7, 2022 Windstorm 861 19% 15 h 11 h 7.2k
Mar 14, 2021 Winter storm 488 11% 20 h 13 h 7.0k
Jun 27, 2017 Thunderstorms 779 17% 21 h 8.2 h 5.9k
May 23, 2021 Thunderstorms 971 22% 25 h 22 h 5.5k
May 22, 2019 Winter storm 1,649 37% 4.8 h 4.8 h 4.9k
May 7, 2024 Windstorm 675 15% 11 h 8.0 h 4.3k
Jul 6, 2025 No storm report 1,120 25% 5.5 h 11 h 4.0k
Feb 17, 2020 No storm report 181 4% 22 h – 3.9k

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 +8h 90% by +10h

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 Custer from twelve hours before it began to its peak. Matching shows coincidence, not proof of cause.

  • Windstorm 71%
  • No storm on record 15%
  • Winter storm 9.2%
  • Thunderstorms 4.7%

Who keeps the lights on

Utilities serving Custer

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

Utility Type Outage min / yr Excl. major storms Outages / yr Residential ¢/kWh Customers
Black Hills Power, Inc. Investor Owned 541 43 2.27 15.1 68k
Black Hills Electric Coop, Inc Cooperative 2,487 120 3.41 14.8 9.4k
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

Across South Dakota

Where it is darkest

Hours / yr64+

All South Dakota 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 4,481 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 →