Moderate M1.2 solar flare erupts at 16:58 UTC on October 17, 2025

A moderate M1.2 solar flare erupted at 16:58 UTC on October 17, 2025.

Today’s flares include multiple M-class and C-class events, though an M1.2 at 16:58 UTC is not directly listed in the available event summary. The day’s M-class flares as reported include an M1.5 flare from region 4246 at 01:28 UTC, an M1.1 flare from the same region at 12:45 UTC, and an M1.0 flare at 14:32 UTC. Several C-class flares also occurred throughout the day, notably from regions 4246 and 4248.

In 24 hours to 12:30 UTC on October 17, solar activity remained at moderate levels with continued M-class flare activity, primarily originating from active region 4246. This region produced several M-class and many C-class flares, while region 4248 remained relatively quiet with minimal changes.

Minor to moderate R1 to R2 radio blackouts are likely through October 18, with a slight chance of an isolated R3 (strong) event due to flare potential from regions 4246 and 4248. Flare probabilities decrease slightly on October 19 as region 4246 moves beyond the western 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, the greater than 2 MeV electron flux reached high levels with a maximum flux of 3 769 pfu observed. 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 due to glancing CME effects, before returning to high levels on October 18 to 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 at nominal levels until 09:30 UTC, when an enhancement occurred in the interplanetary magnetic field, likely due to glancing effects from a CME that departed between October 13 and 15. Total IMF field increased from 6 to 12 nT, with the Bz component moving further southward. Solar wind speeds stayed near 380 km/s. Possible enhancements are anticipated through October 18 from glancing CME influences, with a trend toward more nominal solar wind conditions on October 19.

Geomagnetic field activity ranged from quiet to active levels. G1 – Minor geomagnetic storming is likely on October 17 due to glancing CME effects from events on October 12 and 13. The bulk of the 15 October CMEs is expected to pass ahead of Earth, but unsettled to active geomagnetic activity, and a chance for G1 – Minor storming, persist into early October 19.