Sunspot region AR4366 rotated into view February 1, two weeks after the January 19 X1.9 flare and G4.7 geomagnetic storm. At 23:44 UTC, AR4366 unleashed an X8.1 flare—the 3rd-largest of Cycle 25—triggering an R3 strong radio blackout across Earth's sunlit hemisphere, then fired four more X-class flares (X2.9, X2.8, X1.5, X1.7) within hours. By February 5, it had produced 10 X-class flares in five days and over 100 M-class flares, growing to nearly 10 times Earth's width with a magnetically unstable delta-class configuration.
Multiple coronal mass ejections from AR4366 are forecast to reach Earth between February 5 and 8, possibly triggering G1 minor geomagnetic storms and auroras, with G1 conditions already underway February 5. The January 2026 storm demonstrated the grid's resilience, but this outbreak will test whether recent infrastructure hardening holds against sustained impacts from a single region. Forecasters estimate a 40% probability of more X-class flares and 80% probability of M-class flares continuing through February 7.
Sunspot region AR4366 fires X4.2 flare on February 4-5. Region has now produced 10 X-class flares in 5 days. G1 minor geomagnetic storming ongoing from early-arriving CME. Aurora possible at high latitudes.
AR4366 Fires X1.5 Flare; 9th X-Class in 4 Days
Solar Flare
Sunspot region AR4366 produces X1.5 flare causing R3 strong radio blackout over south Atlantic. Region also produced 15 M-class flares same day.
AR4366 Erupts with M7.2 Flare; 14 M-Class Flares in 24 Hours
Solar Flare
Sunspot region AR4366 produces strongest M-class flare (M7.2) of the outbreak, triggering R2 moderate radio blackout. Region continues relentless flare production.
AR4366 Fires Second X-Class Flare Within Hours
Solar Flare
X2.9 flare erupts from AR4366 less than an hour after X8.1. Reinforces radio blackout conditions across Earth's sunlit hemisphere.
AR4366 Produces X2.8 Flare
Solar Flare
Third X-class flare in rapid succession from newly emerged sunspot region AR4366.
AR4366 Fires X1.5 Flare
Solar Flare
Second X-class flare from AR4366 within 15 minutes of X8.1 eruption.
X8.1 Flare—3rd Largest of Solar Cycle 25
Major Solar Flare
Sunspot region AR4366 erupts with X8.1 flare, the 3rd-largest flare of Solar Cycle 25. Triggers R3 strong radio blackout across Earth's sunlit hemisphere, disrupting HF communications for aviation, maritime, and amateur radio users, especially across Pacific east of Australia and New Zealand.
AR4366 Emerges as Giant Sunspot Region
Solar Feature
New sunspot region AR4366 rotates into Earth-facing view on solar east limb. Region rapidly grows to nearly 10 times Earth's width with magnetically unstable beta-gamma-delta configuration.
January 2026
Storm Subsides After 42-Hour Duration
Storm Resolution
Geomagnetic storm concludes after lasting approximately 42 hours. Peak reached G4.7, close to G5 extreme levels, before gradually declining. Infrastructure impacts minimal despite severity.
Aurora Visible Across Southern U.S. States
Ongoing Impact
Aurora displays continue through January 21, visible as far south as Southern California. Viewing conditions favorable due to new moon phase.
G4 Conditions Continue; Aurora Reaches Southern U.S.
Ongoing Impact
Storm persists through January 20 UTC-day. Northern lights photographed from Alabama, Kentucky, and New Mexico. Power grids report manageable impacts.
Second G4 Peak as Storm Persists
Ongoing Impact
After declining to G2 levels, storm reaches G4 severe conditions again at 08:23 UTC (03:23 EST) and 10:21 UTC (05:21 EST) as CME effects continue.
CME Arrives Early—G4 Storm Begins
Major Storm
CME traveling ~1,700 km/s reaches Earth in 25 hours instead of predicted 40+. G4 severe conditions reached within minutes.
S4 Radiation Storm Declared
Radiation Event
NOAA declares the first S4 severe solar radiation storm since the 2003 Halloween storms. ISS crew shelters in shielded areas.
S4 Radiation Storm Peaks at Highest GOES Record
Radiation Event
High-energy particle shower reaches maximum intensity, placing at top of GOES satellite radiation storm records. Enhanced risk to polar flights and satellites confirmed.
X1.9 Flare Erupts from AR4341
Solar Flare
First X-class flare of 2026 triggers R3-strong radio blackouts across the Americas, Europe, and Africa. Full-halo CME detected.
November 2025
X5.16 Flare Triggers G4 Storm
Major Storm
Region AR4274 produces an X5.16 flare with a 1,950 km/s CME, causing the third-strongest geomagnetic storm of Cycle 25.
October 2024
NASA/NOAA Declare Solar Maximum
Cycle Event
Official announcement that Solar Cycle 25 reached maximum with a smoothed sunspot number of 161—exceeding the predicted peak of 115.
X9.0 Flare—Strongest of Cycle 25
Solar Flare
Sunspot region AR3842 produces an X9.0 flare, the most powerful Earth-facing flare of the current cycle.
May 2024
First G5 Extreme Storm Since 2003
Major Storm
Multiple CMEs from sunspot region 3664 trigger the first G5 storm in 21 years. Aurora visible from Texas to Florida. 40 Starlink satellites lost.
February 2022
Starlink Loses 38 Satellites to Minor Storm
Infrastructure Impact
A G1 geomagnetic storm increases atmospheric drag, causing 38 of 49 newly launched Starlink satellites to reenter and burn up.
December 2019
Solar Cycle 25 Begins
Cycle Event
Solar minimum marks the start of Cycle 25, with a smoothed sunspot number of 1.8.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
1 of 3
March 1989
Quebec Blackout (1989)
On March 13, 1989, a severe geomagnetic storm caused Hydro-Québec's power grid to collapse in under 90 seconds. Telluric currents overwhelmed seven static var compensators in sequence, causing the entire La Grande network to separate. Six million people lost power for nine hours.
Then
Quebec spent $2 billion over six years on grid hardening. U.S. utilities narrowly avoided similar cascading failures.
Now
The blackout drove development of NERC's geomagnetic disturbance standards and modern GIC monitoring. Hydro-Québec engineers believe their current grid would survive a repeat event.
Why this matters now
The 1989 storm remains the benchmark for grid vulnerability. The January 2026 storm, though severe, did not match its intensity—but demonstrated that forecasting gaps still leave operators with limited warning time.
2 of 3
October-November 2003
Halloween Storms (2003)
Three massive sunspot groups produced 17 major flares over two weeks, including an X17 and X10 in rapid succession. CMEs traveling over 2,000 km/s triggered three consecutive G5 storms. The storms knocked out the Japanese ADEOS-II satellite, caused a power outage in Sweden, and disabled 12 transformers in South Africa.
Then
Over half of Earth-orbiting satellites experienced effects. USAF satellite trackers lost position on most LEO assets for days.
Now
The Halloween storms established the modern standard for severe space weather events and drove investment in space weather forecasting infrastructure.
Why this matters now
The January 2026 S4 radiation storm was the first to exceed Halloween 2003 intensity in 23 years, marking a significant return to extreme conditions despite the solar cycle's declining phase.
3 of 3
February 2022
Starlink Satellite Loss (2022)
A minor G1 geomagnetic storm—the lowest severity category—coincided with a Starlink deployment at 210 km altitude. Atmospheric density increased up to 50%, dramatically increasing drag on the 49 newly launched satellites. Despite safe-mode maneuvers, 38 satellites failed to reach operational altitude and burned up during reentry.
Then
SpaceX lost approximately $50 million in satellites. The event demonstrated that even minor storms pose risks during specific operational phases.
Now
Satellite operators adjusted deployment procedures to account for space weather windows. The incident intensified research into thermospheric density forecasting.
Why this matters now
The 2022 loss showed that storm severity ratings alone don't capture operational risk. The January 2026 G4 storm carried similar satellite drag concerns, with operators preemptively entering safe mode.
