We have now officially crossed the S4 / SEVERE radiation storm boundary! The last S4 radiation storm occured on October 29, 2003 before the infamous G5 Halloween storms. This is a historic event. https://t.co/Lq88TKoh7S pic.twitter.com/pDg1fxb6RP
— Vincent Ledvina (@Vincent_Ledvina) January 19, 2026
