NOAA SWPC Forecasting Team

New Capabilities

As of May 2026: Active monitoring and issuing alerts for AR4366 activity

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.

Updated May 22