Minor C9.5 solar flare erupts at 18:25 UTC on May 21, 2026

A minor C9.5 solar flare erupted at 18:25 UTC on May 21, 2026.

Today’s flare activity includes only minor events. The events list for May 21, 2026, does not indicate any X-class or M-class flares. The only reported event is a radio burst observation at 12:04 UTC.

In 24 hours to 12:30 UTC on May 21, solar activity was at very low levels. Region 4441 showed magnetic development, while other sunspot regions were stable or decaying. A coronal mass ejection was observed off the northwest limb, originating near Region 4436.

Solar activity is expected to remain at low levels through May 23, with a slight chance for isolated moderate M-class flares today. Activity may increase on May 22–23 as additional active regions rotate into view.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4436 (N18W78 – Beta), AR 4439 (N06E15 – Alpha), AR 4441 (N07W30 – Beta), and AR 4443 (S16E23 – Alpha).

Over the past 24 hours, electron flux greater than 2 MeV at geosynchronous orbit remained at high levels, peaking at 1 720 pfu. Proton flux above 10 MeV stayed at background levels. The electron flux is expected to decrease to normal or moderate on May 21, then return to high levels May 22–23. Proton flux is predicted to remain at background levels through May 23.

Solar wind parameters trended toward background conditions. Solar wind speeds peaked at 542 km/s early in the period, decreasing to around 430 km/s by the end. The total interplanetary magnetic field reached 6 nT, with a southward Bz maximum of -5 nT. The phi angle was negative. Solar wind should remain near nominal values early on May 21, followed by mild enhancements with a sector boundary crossing. High-speed stream conditions are anticipated May 22–23 from a positive polarity coronal hole high-speed stream.

The geomagnetic field was quiet to unsettled during the past 24 hours. Isolated active periods are likely on May 21 following an expected sector boundary crossing and effects from the approaching high-speed stream. Quiet to unsettled conditions are anticipated for May 22–23 as these influences persist.