Wyoming Power Outages: Widespread Disruptions Hit Western South Dakota and Montana

A large-scale incident of wyoming power outages struck central and northeastern Wyoming on the afternoon of Thursday, November 13, 2025, with service disruptions spreading into western South Dakota and parts of Montana.

The event triggered widespread concern, as thousands of homes, businesses and critical services experienced power loss. In this detailed report we explore what happened, why it happened, who was affected, and what to expect next.

What happened in the Wyoming power outages?

Shortly after 12:40 p.m. MST, multiple utilities reported a major outage across the grid. Rocky Mountain Power (RMP) stated that more than 60 000 customers in Wyoming lost power around 12:40–12:45 p.m. MT. 

Meanwhile, the Western Area Power Administration (WAPA) confirmed that the event began near Medicine Bow, Wyoming when two 500-kilovolt transmission lines tripped, causing an “abnormal voltage event” that cascaded into additional line trips and outages.

Notably, the outage extended beyond Wyoming: utilities in western South Dakota and parts of Montana reported impacted customers, showing the interconnected nature of the grid. 

Which regions and utilities were impacted?

Wyoming: The hardest-hit areas include central and northeastern parts of the state, cities such as Casper, Wyoming, Sheridan, Wyoming, Gillette, Newcastle and Glenrock all reported outages. Some estimates suggest as many as 90 000 to 95 000 customers in Wyoming lost power at peak.

South Dakota & Montana: In western South Dakota, including areas around Rapid City, South Dakota, numerous customers experienced outages and traffic signals went dark, necessitating four-way stops. Utilities such as Black Hills Energy confirmed their systems were impacted by the regional event. 

Utilities’ statements:

• RMP: “At 12:40 p.m. MT a widespread power outage occurred impacting more than 60,000 customers in Wyoming. The cause is currently under investigation.”
• WAPA: “We believe the outage … was triggered by two tripped 500‐kilovolt lines near Medicine Bow. This incident resulted in an abnormal voltage event that subsequently tripped a number of surrounding lines, including WAPA transmission.”

Why did the outage occur?

Triggering event: Two 500 kV transmission lines near Medicine Bow tripped at around 12:45 p.m. The fault led to an abnormal voltage spike which in turn caused additional transmission lines and substations to trip.

Grid instability and cascading failures: According to rural cooperative reports (e.g., Powder River Energy Corporation) voltages were “unstable and are tripping off power.” The utility warned members of “lights on, lights off” as the system stabilization is complex.

Possible external factors: Some officials noted that the aurora borealis was considered as a potential contributing factor to grid interference though this remains unconfirmed.
Related incidents: A fire at the Dave Johnston Power Plant near Glenrock, Wyoming followed the outage. Officials caution the fire was a consequence of the outage, not the cause. 

What immediate impacts are being felt by residents and businesses?

Critical equipment & facilities: Some people dependent on oxygen or medical devices were provided charging stations: e.g., at the waiting room of Memorial Hospital of Converse County in Douglas and the Glenrock Police Department.

Traffic & public safety: In Rapid City and surrounding areas, power to traffic lights was lost and police directed traffic manually.

Businesses & public services: Many businesses closed early, school after-school activities were cancelled, and some public facilities shut down for the day due to the inability to guarantee safe power.

Rural co-ops warnings: For example, Powder River Energy advised members in five northeastern Wyoming counties to “be prepared for an extended outage through the night.” 

What’s the restoration status and what to expect next?

Utility crews are working to bring the system back online, but caution that restoration may take several hours or into the evening because of the complex nature of the event and system-wide instability.

WAPA and other utilities emphasise safety over speed: they will not re-energize lines until voltages are stable in order to avoid damage to transformers or cause further outages.
Customers are urged to monitor official outage maps and announcements via their utility’s website or social media for updates.

What should residents do during the outage of wyoming power outages?

How should individuals respond right now?

• Treat all downed lines as live and dangerous; report them to 911. 
• Conserve cell phone battery by limiting non-essential use and prioritising texts for communication. 
• If using portable generators, never operate them in enclosed spaces; ensure proper ventilation to avoid carbon monoxide risks. 
• Check on vulnerable neighbours, especially those reliant on medical equipment. 
• Once power is restored, gradually turn appliances back on to avoid circuit overload.

Who to contact?
Residents should track updates via their utility’s official outage map or social channels, such as Rocky Mountain Power’s outage site. People needing medical device charging or heating centers should reach out to local emergency management or municipal resources.

Wider implications and grid reliability concerns

This outage underscores the fragility of an interconnected regional transmission system. When high voltage lines trip, the cascade effect can rapidly extend outages across multiple states and utility territories. Experts emphasise that investing in grid resilience, monitoring voltage anomalies proactively and reinforcing infrastructure are critical.

The event may prompt regulatory review of transmission line maintenance, emergency response procedures and coordination among utilities like WAPA, RMP, Black Hills Energy and others.

Final thoughts: What’s next for the wyoming power outages event?

As crews continue to restore service, residents should remain patient and cautious. Full stability across the grid may take into the evening or overnight. Utility officials will likely release more detailed findings about root causes, including the role of the initial 500-kV line trip near Medicine Bow.

For viewers in South Dakota and Montana, the ripple effects of Wyoming’s event highlight the importance of regional readiness for large-scale electrical disruptions.

Conclusion

The wyoming power outages event on November 13, 2025 represents one of the largest recent disruptions in the Mountain West region. Triggered by tripped 500-kilovolt lines and compounded by voltage instability, the outage spread across multiple states and affected tens of thousands of customers. With utilities prioritising safe restoration and urging caution among residents, the situation serves as a key reminder of grid vulnerabilities and the importance of preparedness. Stay tuned to local utility updates, heed safety guidance, and prepare for potential further ripple effects as investigations continue.

Disclaimer

The content shared by Meyka AI PTY LTD is solely for research and informational purposes.  Meyka is not a financial advisory service, and the information provided should not be considered investment or trading advice.