Minor C9.1 solar flare erupts at 03:45 UTC on October 15, 2025

A minor C9.1 solar flare erupted at 03:45 UTC on October 15, 2025.

Today’s flares include a C-class event beginning at 00:29 UTC and ending at 00:42 UTC, as well as a brief C-class event at 00:34 UTC. No X-class or M-class flares have been reported for the period.

In 24 hours to 00:30 UTC on October 15, solar activity remained at moderate levels with M-class flares recorded on October 14. Multiple C-class flares were produced primarily by complex regions, and no new Earth-directed coronal mass ejections were detected.

Minor to moderate (R1-R2) radio blackouts are likely over the next three days, with a slight chance for an isolated strong R3 radio blackout event due to ongoing solar activity.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N22W43 – Beta-Gamma-Delta), AR 4248 (N07W13 – Beta-Gamma-Delta), AR 4250 (N07W07 – Beta), AR 4251 (N19E12 – Alpha), AR 4252 (S13E38 – Alpha), and AR 4254 (N10E74 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, with a maximum flux of 5 130 pfu observed. The greater than 10 MeV proton flux remained at background values. The greater than 2 MeV electron flux is expected to return to nominal to moderate levels on October 15-16, with a slight chance for a solar radiation storm above the S1 – Minor level through October 17.

Solar wind parameters slowly returned to nominal values as the effects of a negative coronal hole high-speed stream diminished, with total interplanetary magnetic field at or below 5 nT and solar wind speeds decreasing from 700 km/s to 550 km/s. Solar wind conditions are expected to gradually normalize over October 15, with disturbed conditions likely by late October 15 and continuing through October 17 due to CME arrivals from previous days.

Geomagnetic field activity was quiet to unsettled over the past 24 hours. The geomagnetic field is expected to remain unsettled to active until late October 15 as CME impacts are anticipated. Moderate G2 – Moderate geomagnetic storms are likely on October 16, followed by G1 – Minor storming into October 17.