Moderate M1.0 solar flare erupts at 15:58 UTC on December 19, 2025

A moderate M1.0 solar flare erupted at 15:58 UTC on December 19, 2025.

Today’s flare activity includes several minor C-class events: a C1.9 flare at 05:43 UTC from region 4307, a C1.3 flare at 05:58 UTC also from region 4307, a C1.7 flare at 06:20 UTC from region 4307, and a C2.2 flare at 13:43 UTC. No X- or other M-class flares were listed up to the latest event log update.

In 24 hours to 12:30 UTC on December 19, solar activity was at low levels. No Earth-directed coronal mass ejections were detected in available coronagraph imagery.

Solar activity is expected to continue at low levels through December 21, 2025.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4305 (S25W89 – Alpha), AR 4307 (S15W88 – Beta), AR 4308 (N08W27 – Alpha), AR 4310 (N02W66 – Beta), AR 4311 (N03W12 – Beta), AR 4312 (N18E62 – Alpha), and AR 4313 (S14E29 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, with a peak flux of 2 690 pfu observed. The greater than 10 MeV proton flux remained at background levels. Elevated electron flux is expected to persist from December 19 to 21, with proton flux continuing near background levels.

The solar wind environment was mildly enhanced under ongoing negative polarity coronal hole high-speed stream influences. Total field strength reached 8 nT early in the period, with Bz fluctuations between +/-5 nT. Wind speeds gradually decreased from approximately 615 km/s to 530 km/s. Mildly enhanced solar wind conditions will persist through December 20 as high-speed stream effects wane, with background conditions anticipated by December 21.

The geomagnetic field was quiet and unsettled under persistent negative polarity coronal hole influence. These conditions are expected to continue through December 20 as the high-speed stream influence diminishes, with mostly quiet conditions prevailing by December 21.