Rare S3 – Strong solar radiation storm in progress after X1.9 flare on January 18
A strong solar radiation storm (S3) is in progress after ≥10 MeV proton flux exceeded 1 000 pfu at 10:20 UTC on January 19, 2026. The event follows an X1.9 solar flare and full-halo coronal mass ejection that erupted on January 18. S3 – Strong solar radiation storms are relatively rare, occurring just a few times in one 11-year solar cycle.









