Moderate M1.8 solar flare erupts at 20:15 UTC on October 19, 2025

A moderate M1.8 solar flare erupted at 20:15 UTC on October 19, 2025.

A review of today’s solar flare activity shows that the highest confirmed event was a moderate M1.0 flare that began at 01:46 UTC, peaked at 01:56 UTC, and ended at 02:04 UTC from region 4246. Additional flares included a C2.8 flare at 04:34 UTC from region 4246, a C4.7 at 08:02 UTC from region 4246, a C2.6 at 12:42 UTC from region 4256, a C2.9 at 13:42 UTC, a C2.4 at 16:13 UTC, and a C3.7 at 18:22 UTC.

In 24 hours to 12:30 UTC on October 19, solar activity reached moderate levels. Most flare activity originated from region 4246 beyond the west limb, including an M1.0 flare. No Earth-directed CMEs were observed.

Solar activity is expected to remain low, with the chance for isolated M-class flares (R1-R2/Minor-Moderate) from October 19 to 21.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N25W93 – Beta), AR 4248 (N07W66 – Beta), AR 4252 (S12W14 – Beta), AR 4254 (N10E20 – Alpha), AR 4256 (S15E40 – Beta), AR 4257 (S10E60 – Alpha), and AR 4258 (S16W40 – Beta).

Over the past 24 hours, the greater than 2 MeV electron flux was at normal to moderate levels. The greater than 10 MeV proton flux remained at background levels. The greater than 2 MeV electron flux is expected to stay at normal to moderate levels on October 19 and increase to high levels October 20–21. The greater than 10 MeV proton flux is expected to remain at background levels through October 21.

Solar wind parameters were enhanced due to a combination of CME and negative polarity coronal hole high-speed stream influences. Total magnetic field strength reached 15 nT and the Bz component was sustained southward by up to -12 nT between 15:30 UTC and 20:15 UTC on October 18. Solar wind speeds ranged from 400–580 km/s. Enhanced solar wind conditions and negative polarity CH HSS influences are expected to prevail through October 21.

The geomagnetic field reached G1-G2 (Minor-Moderate) storm levels in response to these influences. Periods of active geomagnetic conditions are likely over October 19–20, with a chance for G1 (Minor) storms on October 19. Conditions are likely to become quiet to unsettled on October 21 as CH HSS effects wane.