Moderate M1.0 solar flare erupts at 23:19 UTC on October 16, 2025

A moderate M1.0 solar flare erupted at 23:19 UTC on October 16, 2025.

Today’s flares include an M1.3 flare from region 4246 peaking at 14:08 UTC, and an M1.1 flare from the same region peaking at 19:16 UTC. Multiple C-class flares, with peak classes between C3.3 and C8.4, also occurred, primarily from region 4246. No X-class flares were detected.

In 24 hours to 12:30 UTC on October 16, solar activity continued at moderate levels with notable M-class flares from region 4246. Several C-class events were also observed as active regions evolved.

Minor to moderate (R1-R2) radio blackouts are likely through October 18, with a slight chance for an isolated R3 (Strong) event due to ongoing flare activity.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N22W56 – Beta-Gamma-Delta), AR 4248 (N07W27 – Beta-Gamma-Delta), AR 4250 (N07W21 – Alpha), AR 4252 (S13E28 – Beta), and AR 4254 (N10E60 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, with a maximum of 2 850 pfu observed. The greater than 10 MeV proton flux remained at background levels. There is a slight chance for an event above the S1 – Minor threshold through October 18.

Solar wind parameters were slowly returning to nominal levels as coronal hole high speed stream effects waned. The total interplanetary magnetic field remained at or below 6 nT, with the Bz component between +3 and -4 nT. Solar wind speeds decreased from around 520 km/s to 450 km/s. Gradually waning conditions are expected, but disturbed levels are anticipated late on October 16 through October 18 due to upcoming CME arrivals.

Geomagnetic field activity was mostly quiet. G2 – Moderate geomagnetic storm levels are likely late on October 16 in response to recent CME arrivals, with G1 – Minor storm activity expected to continue into October 17 and 18.