Minor C7.7 solar flare erupts at 01:44 UTC on October 15, 2025

A minor C7.7 solar flare erupted at 01:44 UTC on October 15, 2025.

Today’s flares include a C-class event (C7.7) beginning at 00:29 UTC and ending at 00:42 UTC, and another event at 00:34 UTC recorded as a radio burst.

In 24 hours to 00:30 UTC on October 15, solar activity continued at moderate levels due to M-class flare activity. Region 4246 produced an M2.0 flare peaking at 00:41 UTC and an M3.1 flare at 20:36 UTC on October 14. Region 4248 was responsible for an M2.0 flare at 12:47 UTC on October 14. Both regions continued to grow in size and complexity, producing the majority of C-class flares during the period. No new Earth-directed coronal mass ejections were observed.

Minor to moderate (R1-R2) radio blackouts are likely for the next three days, with a slight chance for an isolated strong (R3) event due to activity in 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 with a maximum flux of 5 130 pfu observed. 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. There is a slight chance for a greater than 10 MeV proton event above S1 – Minor levels through October 17.

In the past day, solar wind parameters were slowly returning to nominal levels as the effect of the negative CH HSS waned. Total interplanetary magnetic field stayed at or below 5 nT, with isolated negative Bz periods. Solar wind speeds declined from about 700 km/s to 550 km/s. Solar wind parameters are expected to continue gradual waning over October 15 as negative CH HSS influence decreases. Disturbed conditions are forecast for late October 15 through October 17 due to CME arrivals from October 11–13.

Geomagnetic field activity was quiet to unsettled over the past 24 hours. The geomagnetic field will likely remain unsettled to active until late on October 15 when CMEs from October 11–13 begin to impact the near-Earth environment. Moderate (G2) storming is likely on October 16, with minor (G1) storming possible into October 17.