Rare Severe Solar Storm Lights Up Skies Far South as NOAA Issues S4 Radiation, G4 Geomagnetic Alerts

People as far south as Kansas, Colorado and possibly Texas stepped outside Monday night to find curtains of green and purple light rippling across the sky — a display of northern lights normally confined to Alaska or Scandinavia.

Behind the scenes, airlines, satellite operators and power grid managers were focused on a less visible spectacle: one of the most intense combinations of solar radiation and geomagnetic activity to hit Earth in more than two decades.

A chain of eruptions from an active sunspot region

Since Sunday, an active region on the sun has unleashed a chain of eruptions that produced a powerful X‑class flare, a fast-moving cloud of magnetized plasma aimed squarely at Earth and a rare solar radiation storm strong enough for federal forecasters to invoke a level they had not used since 2003.

The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center in Boulder, Colorado, reported that sunspot Region 4341 fired an X1.9‑class flare at 1:09 p.m. EST Sunday. The blast triggered what NOAA classifies as an R3 (“strong”) radio blackout on the sunlit side of Earth, briefly disrupting some high‑frequency communications and navigation signals.

Coronagraph images from spacecraft monitoring the sun showed a full‑halo coronal mass ejection (CME) — a swelling ring of plasma expanding outward in all directions — with Earth directly in its path.

By early Monday, radiation from the event had begun to wash over the planet.

NOAA declares rare S4 solar radiation storm

Instruments aboard NOAA’s GOES‑19 satellite recorded a surge in high‑energy protons, pushing space‑weather conditions through several tiers of the agency’s five‑step radiation scale. Just before 1 p.m. EST Monday, forecasters formally declared an S4 solar radiation storm, the second‑highest level.

“An S4 (Severe) solar radiation storm is in progress,” the center said in a bulletin issued at 1:54 p.m. EST.

Measurements from GOES‑19, it said, showed the storm had “intensified to Severe (S4) … and it is still increasing.”

Forecasters called the event “a rare occurrence” and said the intensity of incoming particles “exceeds the intensity during the October 2003 ‘Halloween’ space weather storms,” a notorious series of solar eruptions that disrupted satellites and knocked power offline in parts of Sweden.

Shawn Dahl, a service coordinator at the Space Weather Prediction Center, told reporters this week the current storm ranks as the strongest of its kind in more than 20 years, underscoring how unusual it is to see radiation levels at S4.

S4 conditions mean very high fluxes of energetic protons bombarding the space around Earth. That raises radiation exposure for satellites and for humans at high altitude and high latitude, particularly aircraft on polar routes and astronauts outside the protection of their spacecraft.

NOAA said it had notified airlines, the Federal Aviation Administration, NASA, the Federal Emergency Management Agency, the North American Electric Reliability Corporation and other operators “to support preparedness actions as conditions evolve.”

Above the atmosphere, mission controllers typically respond to such storms by adjusting satellite operations, placing some instruments in safe mode and watching closely for so‑called single‑event upsets — bit flips and glitches caused when energetic particles strike electronics.

Astronauts aboard the International Space Station are expected to remain safe inside the station’s shielding and under the partial protection of Earth’s magnetic field. During past storms of this magnitude, however, NASA has typically postponed planned spacewalks to limit crew exposure.

CME impact pushes geomagnetic storm to G4

If the rising radiation were not enough, the main shock wave of the coronal mass ejection slammed into Earth’s magnetic field Monday afternoon.

Sensors positioned between Earth and the sun detected the CME’s leading edge shortly after 2 p.m. EST. Within roughly half an hour, Earth’s geomagnetic indices — which track how violently the planet’s magnetic field is shaking — shot from relatively mild disturbance to what NOAA classifies as G4 (“severe”) on its five‑level geomagnetic storm scale.

“G4 levels were first reached at 2:38 p.m. EST (1938 UTC) on 19 January, 2026 upon CME shock arrival,” the center said.

A follow‑up alert early Tuesday reported that G4 conditions were reached again at 3:23 a.m. and 5:21 a.m. EST, indicating a prolonged episode of severe storming as different parts of the plasma cloud and its embedded magnetic field swept past Earth.

G4 storms can induce powerful electrical currents in long transmission lines, pipelines and rail systems; cause voltage control problems in electric grids; and disturb satellite orbits and radio communications. They also greatly expand the region where auroras are visible, pushing the shimmering lights far beyond their usual high‑latitude confines.

Auroras spread across the U.S. and abroad

Forecasts ahead of Monday night suggested that, if skies were clear, people across most of Canada and a swath of the northern United States could have a chance to see the aurora. Forecasters said the lights could dip into the central Plains and possibly as far south as northern Alabama, northern California and parts of Texas.

Local meteorologists from Alabama to Colorado devoted segments to explaining where and when to look, advising viewers to head away from city glare after dark and to use smartphone night modes to capture faint reds and purples that might not be obvious to the naked eye.

Reports and images shared on social media late Monday and early Tuesday showed pillars and arcs of green stretching over Midwestern farm fields and Western mountain towns, as well as bright displays in northern Europe and parts of Asia.

Infrastructure operators monitor grid, aviation and GPS risks

While the lights drew people into the cold, operators of critical infrastructure focused on keeping systems running smoothly.

On the ground, the agency’s notice to the North American Electric Reliability Corporation signaled that high‑voltage grid operators across the United States and Canada were on heightened alert. During severe geomagnetic storms, utilities can take steps such as reducing power transfers, adjusting voltage settings and closely monitoring transformers for unusual heating caused by geomagnetically induced currents.

As of midday Tuesday, no major, widespread power outages had been publicly linked to the storm. Space‑weather experts cautioned that even when grid problems do not rise to the level of blackouts, storms of this magnitude can create operational challenges and stress aging equipment, especially in higher‑latitude regions.

In the air, the combination of increased radiation and degraded high‑frequency radio is of particular concern for long‑haul flights that cross the Arctic, where aircraft rely more heavily on HF communications and where satellite coverage can be patchier. Airlines have previously rerouted polar flights during strong solar storms, adding time and fuel costs but reducing radiation doses and avoiding areas of poor communication.

Several outlets reported that some carriers were adjusting routes on Monday and Tuesday, though there were no reports of safety incidents tied to the solar activity.

The storm also raised the risk of temporary disruptions to GPS signals and other satellite‑based navigation and timing services, especially at high latitudes. That can affect precision agriculture, surveying, offshore drilling and any industry that depends on centimeter‑level positioning or highly accurate timing.

The Space Weather Prediction Center stressed that its alerts describe potential impacts and that actual effects depend on many factors, including local infrastructure, storm duration and the orientation of the solar magnetic field as it interacts with Earth’s.

A test during Solar Cycle 25

The episode comes as the sun nears the peak of its roughly 11‑year activity cycle, known as Solar Cycle 25. During solar maximum, large sunspot groups and powerful flares become more common, and with them the risk of major geomagnetic and radiation storms.

In recent years, several G4 and even G5 geomagnetic storms have produced spectacular auroras at low latitudes without triggering the kind of cascading failures that worry planners. Scientists and regulators say that is due in part to investments made after past events, including the 2003 storms, to harden grids and improve procedures, and in part to the particular geometry and timing of each solar blast.

For researchers, this week’s S4–G4 “double punch” offers a rich trove of data on how the sun accelerates particles and how those particles and magnetic fields interact with Earth. For operators, it serves as a real‑world test of contingency plans that are typically rehearsed on paper and in simulations.

And for many people who had never seen the northern lights before, it provided a vivid, if chilly, reminder that the sun is not a static backdrop in the sky but a dynamic star whose outbursts can, in rare moments, paint the heavens and tug at the technology woven through daily life.