Moderate M3.7 solar flare erupts at 07:18 UTC on October 15, 2025

A moderate M3.7 solar flare erupted at 07:18 UTC on October 15, 2025.

Today’s flares include a M4.8 flare from region 4246 peaking at 04:15 UTC, and C-class events including C7.7 at 01:44 UTC, C5.6 at 03:14 UTC, and C9.1 at 03:45 UTC, all from region 4246. No X-class activity was recorded.

In 24 hours to 00:30 UTC on October 15, solar activity continued at moderate levels due to M-class flare activity. Regions 4246 and 4248 produced several M-class and multiple C-class flares. 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 a strong (R3) event due to ongoing flare activity from active regions.

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, while the greater than 10 MeV proton flux remained at background values. Electron flux is expected to return to nominal to moderate levels on October 15–16, with a slight chance for a solar radiation storm at S1 – Minor levels through October 17.

Solar wind parameters were slowly returning to nominal as the negative coronal hole high speed stream influence waned, with interplanetary magnetic field generally at or below 5 nT and wind speeds gradually decreasing from about 700 km/s to 550 km/s. Gradual waning is expected through October 15, with disturbed solar wind conditions possible late October 15 through October 17 due to earlier CME arrivals.

Geomagnetic field activity was quiet to unsettled during the past 24 hours. Conditions are likely to remain unsettled to active until late October 15, with moderate storming (G2 – Moderate) expected on October 16 as CME impacts are predicted to peak. Minor storming (G1 – Minor) may persist into October 17.