Severe G4 Geomagnetic Storm Sparks Rare Northern Lights Spectacle Across 24 US States

Millions of people across the United States were treated to a rare celestial display on Monday night as the Northern Lights, or Aurora Borealis, pushed unusually far south into the mid-latitude regions. The phenomenon was triggered by a 'severe' G4-level geomagnetic storm, the result of a massive solar eruption that occurred over the weekend.

The National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Center (SWPC) issued a rare G4 geomagnetic storm watch for Monday, 19 January 2026, after a fast-moving Coronal Mass Ejection (CME) collided with Earth's magnetic field earlier than anticipated. The storm reached severe levels at approximately 2:38 p.m. EST (1938 GMT) on Monday, as reported by Space.com.

The Science of the 'Halo' CME

The current surge in auroral activity is tied to an X1.9-class solar flare—one of the most powerful categories of solar eruptions—which launched from sunspot region AR4341 on 18 January. This flare released a 'full-halo' CME, a vast cloud of solar plasma and magnetic fields directed squarely at Earth.

While typical CMEs can take up to three or four days to reach the planet, this specific event was clocked at a velocity exceeding 1,000 km/s, allowing it to bridge the 93-million-mile gap in just over 25 hours. According to The Weather Network, the intensity and speed of the impact caused Earth's magnetic field to 'rattle hard,' sending charged particles cascading toward the poles and illuminating the atmosphere.

Visibility Reach and Optimal Viewing

Under G4 conditions, the aurora's 'view line'—the southernmost limit where the lights can be seen on the northern horizon—extended well beyond the usual Canadian border states. Forecasts suggested that residents as far south as Northern California, Oklahoma, and even portions of Alabama and Georgia might witness a faint glow, provided they were away from city light pollution.

The primary 'front-row seats' included 24 states ranging from Washington and Montana to New York and Maine. For mid-latitude regions like Nebraska, Iowa, and Pennsylvania, the lights appeared more vivid through long-exposure photography, which can capture colours invisible to the naked eye. According to People.com, the lack of moonlight due to the recent new moon provided a 'perfect dark canvas' for the display.

Impact on Infrastructure and Satellites

While the Northern Lights provide a stunning visual, G4 storms are classified as 'severe' due to their potential to disrupt critical technology. NOAA warned that such events can cause widespread voltage control problems on power grids and lead to 'surface charging' on satellites, which may require orientation corrections from ground control.

The high-energy particles associated with the S4 solar radiation storm also pose risks to high-altitude flight crews and passengers near the Arctic. 'A storm of this magnitude hasn't been seen in more than two decades,' said Shawn Dahl, service coordinator at the SWPC, as cited by The Telegraph.

As the Sun approaches its 'solar maximum'—the peak of its 11-year activity cycle—experts anticipate that these high-impact space weather events will become increasingly common throughout 2026. EarthSky notes that while the storm is expected to ease into Tuesday, a lingering G3 (strong) watch remains in place for the early hours of 21 January.