Moderate M1.0 solar flare erupts at 14:32 UTC on October 17, 2025

A moderate M1.0 solar flare erupted at 14:32 UTC on October 17, 2025.

This flare began at 14:22 UTC and ended at 14:36 UTC, originating from sunspot region 4246. Today’s flares include M1.5 at 01:28 UTC from region 4246, M1.1 at 12:45 UTC from region 4246, and M1.0 at 14:32 UTC from region 4246. Several C-class events were also observed, notably C8.0 at 05:54 UTC from region 4248.

In 24 hours to 12:30 UTC on October 17, solar activity remained at moderate levels with multiple M-class and C-class flares, primarily from region 4246. Region 4248 was relatively quiet and regions 4255 and 4256 showed new or evolving activity.

Minor to moderate (R1-R2) radio blackouts are likely through October 18, with a slight chance for an isolated strong (R3) blackout due to active regions 4246 and 4248. Probabilities decrease slightly on October 19 as region 4246 rotates beyond the limb.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N24W69 – Beta-Gamma-Delta), AR 4248 (N07W41 – Beta-Gamma), AR 4250 (N05W34 – Alpha), AR 4252 (S13E14 – Beta), AR 4254 (N10E46 – Alpha), AR 4255 (S08E38 – Beta), and AR 4256 (S16E66 – Beta).

Over the past 24 hours, greater than 2 MeV electron flux reached high levels, peaking at 3 769 pfu. The greater than 10 MeV proton flux remained at background levels. The electron flux is expected to decrease to normal to moderate levels on October 17, then return to high levels on October 18–19. There is a slight chance for a greater than 10 MeV proton event above S1 – Minor levels through October 18.

Solar wind parameters were nominal until an enhancement occurred after 09:30 UTC, likely due to glancing effects from recent CMEs. The total interplanetary magnetic field rose to 12 nT, with the Bz component reaching -9 nT. Solar wind speeds remained near 380 km/s. Further enhancements are possible through October 18 with a return to nominal conditions expected by October 19.

Geomagnetic field activity was at quiet to active levels. G1 – Minor geomagnetic storming is likely on October 17 due to glancing CME effects and may continue into October 18, with unsettled to active geomagnetic conditions and a chance for additional G1 – Minor storm periods early on October 19.