Strong M5.1 solar flare erupts at 01:50 UTC on December 27, 2025

A strong M5.1 solar flare erupted at 01:50 UTC on December 27, 2025.

Today’s flares include a C4.8 event from region 4324 starting at 00:23 UTC, with peak at 00:32 UTC and ending at 00:38 UTC. Several radio bursts (RSP, RBR) are reported; no X-class or other M-class flare is included in the event list at this time.

In 24 hours to 00:30 UTC on December 27, solar activity was low. The majority of activity came from region 4323, producing the largest flare of C6.9 at 09:14 UTC on December 26. Slight decay was observed in the trailing spots of region 4317, and new region 4324 was numbered. The remainder of the regions were either stable or in decay, and no Earth-directed CMEs were observed.

Solar activity is expected to be low with a chance for M-class flares through December 29.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4312 (N19W48 – Alpha), AR 4316 (S08W45 – Alpha), AR 4317 (N11W06 – Beta), AR 4319 (S10E15 – Beta), AR 4320 (N05E27 – Alpha), AR 4321 (S10W36 – Beta-Delta), AR 4322 (N13W77 – Beta), AR 4323 (S12E61 – Alpha), and AR 4324 (N28E75 – Beta).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels with a peak flux of 8 194 pfu and the greater than 10 MeV proton flux remained at background levels. High electron flux is expected to continue on December 27 and 28, returning to normal to moderate on December 29. The greater than 10 MeV proton flux is expected to persist at background levels.

Solar wind parameters were in decline as coronal hole high speed stream effects diminished. Solar wind speed decreased from approximately 550 km/s to about 500 km/s, with total field ranging from 2–6 nT and Bz between +/-5 nT. The phi angle was predominantly positive. Mostly quiet solar wind conditions are expected through December 29.

The geomagnetic field was at quiet to unsettled levels over the past 24 hours. Quiet conditions are expected to prevail as CH HSS effects decay through December 29.