Moderate M1.5 solar flare erupts at 01:28 UTC on October 17, 2025

A moderate M1.5 solar flare erupted at 01:28 UTC on October 17, 2025.

Today’s flares include only reported M-class activity according to available event listings. No X-class flares have been reported. There are no event reports specified for October 17, 2025.

In 24 hours to 00:30 UTC on October 17, solar activity reached moderate levels with M-class flare activity. Multiple M-class flares were recorded from various regions. No Earth-directed coronal mass ejections (CMEs) were detected in the available imagery.

Minor to moderate (R1-R2) radio blackouts are likely through October 18, with a slight chance for an isolated R3 (Strong) event due to current and potential flare activity. The probability of these events decreases 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, the greater than 2 MeV electron flux reached high levels, with a maximum flux of 3 769 pfu observed at 20:15 UTC on October 16. The greater than 10 MeV proton flux remained at background levels. The greater than 2 MeV electron flux is expected to decrease to normal to moderate levels on October 17 due to glancing CME effects, returning to high levels on October 18–19. There is a slight chance for a greater than 10 MeV proton event above the S1 – Minor level through October 18.

Solar wind parameters reflected a mildly disturbed environment, with total field values ranging from 2–5 nT and Bz near neutral. Solar wind speeds decreased from approximately 470 km/s to around 400 km/s but rose again to 430–450 km/s near 20:00 UTC on October 16. Phi rotated between positive and negative sectors. Additional solar wind enhancements are anticipated through October 18 due to glancing CME influences from recent solar events. A trend towards a more nominal environment is expected on October 19.

Geomagnetic field activity was at quiet levels over the past 24 hours. G1 – Minor geomagnetic storming is likely on October 17 due to glancing CME effects from events that left the Sun on October 12–13. Unsettled to active geomagnetic activity, with the chance for another G1 – Minor storm, is also possible on October 18, with any effects possibly carrying into early October 19.