Moderate M2.4 solar flare erupts at 23:45 UTC on October 15, 2025

A moderate M2.4 solar flare erupted at 23:45 UTC on October 15, 2025.

Today’s flares include no edited event reports as of October 16, 2025.

In 24 hours to 12:30 UTC on October 15, solar activity remained at moderate levels due to multiple M-class flares. The largest event was an M4.8 flare peaking at 04:15 UTC on October 15. Additional moderate M-class activity occurred during this period along with a number of C-class flares.

Minor to moderate (R1-R2) radio blackouts are likely over the next three days, with a slight chance for an isolated R3 (Strong) event due to ongoing and potential M-class flare 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 (S13E31 – Alpha), and AR 4254 (N10E74 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, with 5,130 pfu observed at 15:50 UTC on October 14. 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.

Solar wind parameters were gradually returning to nominal levels over the past 24 hours as the influence of a negative CH HSS waned. Solar wind speeds decreased from approximately 700 km/s to 550 km/s. The total interplanetary magnetic field stayed at or below 6 nT. Solar wind conditions are expected to continue a gradual waning on October 15, with disturbed conditions anticipated by late October 15 and continuing through October 17, due to CME arrivals from October 11–13.

Geomagnetic field activity was quiet to unsettled during the last 24 hours. The geomagnetic field is likely to remain unsettled to active until late October 15, when CME impacts from October 11–13 are expected to begin affecting near-Earth space. Moderate storming conditions (G2 – Moderate) are likely on October 16, with minor storming (G1 – Minor) possible into October 17.