Following an X1.9 flare and associated full halo coronal mass ejection (CME) late on January 18, 2026, the ≥10 MeV proton flux rose above 100 pfu early on January 19. The event reached S2 – Moderate solar radiation storm levels, prompting extended warnings for continued elevated radiation conditions through the rest of the day.
Full halo coronal mass ejection (CME) produced by long-duration X1.9 solar flare on January 18, 2026. Credit: NASA SDO, NASA/ESA LASCO, Helioviewer, The Watchers
A solar radiation storm is currently in progress after a long-duration X1.9 solar flare from Active Region 4341 (S11E24), which peaked at 18:09 UTC on January 18. The eruption produced Type II and Type IV radio emissions and a 3 200 sfu F10.7 radio burst with a Castelli-U signature.
A full halo coronal mass ejection (CME) was first detected in GOES CCOR-1 imagery at approximately 18:30 UTC.
The ≥10 MeV proton flux initially surpassed 10 pfu at 22:55 UTC on January 18 (S1 – Minor) and then exceeded 100 pfu at 04:40 UTC on January 19, reaching S2 – Moderate levels.
At S2 – Moderate radiation storm intensity, radiation exposure for high-latitude and high-altitude flights may increase slightly, and satellite systems may experience occasional single-event upsets or surface charging. Minor high-frequency radio fades are possible at polar latitudes.
The Space Weather Prediction Center (SWPC) upgraded its warning for proton flux persistence through 23:59 UTC on January 19. Real-time GOES proton plots confirm a sustained rise in particle flux above the S1 threshold.
Moderate flare potential remains from Region 4341 through January 21, and the associated CME could intensify geomagnetic conditions on January 19–20, depending on its magnetic orientation. Geomagnetic activity is currently quiet to active under positive-polarity coronal-hole influence, but higher storm levels are possible once the CME reaches Earth.
An additional high-electron-flux alert, active since January 12, indicates continued charging risk for satellites. Yesterday’s maximum ≥2 MeV electron flux reached 4 619 pfu under the same coronal-hole regime.
