Moderate M1.1 solar flare erupts at 12:45 UTC on October 17, 2025

A moderate M1.1 solar flare erupted at 12:45 UTC on October 17, 2025.

Today’s flare activity includes several M-class and C-class events. Confirmed moderate M-class flares include: M1.5 (peak 01:28 UTC, AR 4246), M1.1 (peak 12:45 UTC, AR 4246), M1.0 (peak 14:32 UTC, AR 4246), M1.3 (peak 16:32 UTC, AR 4246), and M1.2 (peak 16:58 UTC, AR 4246). Additional activity includes numerous C-class flares, primarily from AR 4246 and AR 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, mainly originating from AR 4246. AR 4248 was relatively quiet, while new regions AR 4255 and AR 4256 were numbered, with 4256 showing signs of rapid evolution. No Earth-directed coronal mass ejections were observed.

Minor to moderate (R1-R2) radio blackouts are likely through October 18, with a slight chance for an isolated R3 (Strong) event due to the continuing activity from regions 4246 and 4248. Probabilities decrease slightly on October 19.

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 with a maximum of 3 769 pfu. Greater than 10 MeV proton flux remained at background. The electron flux is expected to decrease to normal or moderate levels on October 17 due to CME effects, before returning to high levels on October 18-19. There is a slight chance for a solar radiation storm above S1 – Minor levels through October 18.

Solar wind parameters were nominal until 09:30 UTC on October 17, when interplanetary magnetic field enhancement possibly related to earlier CMEs raised total field strength and produced a southward Bz. Solar wind speed remained near 380 km/s. Possible enhancements are anticipated through October 18 due to ongoing glancing CME influences, with a return to nominal conditions expected by October 19.

Geomagnetic activity was quiet to active in the past 24 hours. G1 – Minor geomagnetic storming is expected on October 17 from glancing CME effects, with unsettled to active levels and a chance for G1 on October 18. Activity should gradually return to quieter conditions by October 19.