Minor C8.3 solar flare erupts at 18:07 UTC on October 15, 2025

A minor C8.3 solar flare erupted at 18:07 UTC on October 15, 2025.

Today’s flares include a moderate M4.8 solar flare from region 4246 peaking at 04:15 UTC, followed by an M3.7 at 07:18 UTC and an M1.1 at 14:10 UTC, all from region 4246. Numerous minor C-class flares were also observed with peak times including a C9.1 at 03:45 UTC, a C7.7 at 01:44 UTC, and a C8.3 at 18:07 UTC.

In 24 hours to 12:30 UTC on October 15, solar activity continued at moderate levels, driven primarily by multiple M-class flare events. The majority of these flares originated from region 4246, which produced the largest flare, an M4.8 at 04:15 UTC. Region 4248 produced additional M-class activity, and other regions contributed minor C-class events.

There is a likelihood of minor to moderate (R1–R2) radio blackouts over the next three days, with a slight possibility of an isolated R3 (strong) event due to active regions 4246 and 4248.

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, peaking at 5 130 pfu, while the greater than 10 MeV proton flux remained at background levels. 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 greater than 10 MeV proton event above the S1 – Minor level through October 17.

Solar wind parameters were slowly returning to nominal levels as the effect of the negative CH high-speed stream waned. Interplanetary magnetic field values remained at or below 6 nT. Wind speeds decreased from approximately 700 km/s to 550 km/s. Solar wind conditions are expected to continue gradual waning on October 15, with disturbed solar wind expected late on October 15 and continuing through October 17 due to CME arrivals from activity in AR 4246 between October 11–13.

Geomagnetic field activity was quiet to unsettled in the past 24 hours. The geomagnetic field is likely to remain unsettled to active until late on October 15, after which CMEs from October 11–13 are expected to impact the near-Earth environment, with G2 – Moderate storming conditions likely on October 16 and G1 – Minor storming likely continuing into October 17.