Global geomagnetic conditions escalated to moderate storm levels (NOAA Kp 6+ ) between 21:00 UTC on December 10 and 00:00 UTC on December 11 and are currently at quiet levels (NOAA Kp 2 + ). Locally, geomagnetic conditions reached moderate storm levels (K BEL 6) between 23:00 UTC on December 10 and 01:00 UTC on December 11. The geomagnetic storm was likely the result of a glancing blow arrival associated with the Coronal Mass Ejection (SIDC CME 607) observed on December 8. An increase in solar wind parameters was observed around 20:00 UTC on December 10. Solar wind speeds rose from approximately 400 km/s to 450 km/s, and the interplanetary magnetic field strength increased from 2 nT to 18 nT. From 20:00 UTC on December 10 to 02:00 UTC on December 11, there was a prolonged interval of negative Bz, with values reaching a minimum of –16 nT. Further minor to moderate geomagnetic storm conditions remain possible in the coming hours.

Solar flaring activity was low over the past 24 hours, with only C-class flares. The strongest flare was a C2.8 flare (SIDC Flare 6419) peaking at 13:04 UTC on December 13. It was associated with SIDC Sunspot Group 718 (NOAA Active Region 4304, magnetic type beta). There are currently four numbered active regions on the solar disk. The most complex one is SIDC Sunspot Group 722 (NOAA Active Region 4307) with magnetic type beta-gamma. SIDC Sunspot Group 712 (NOAA Active Region 4296) has rotated across the west limb. SIDC Sunspot Group 724 has decayed into a plage. The solar flaring activity is expected to be low over the next 24 hours, with C-class flares very likely and a chance for M-class flares. No Earth-directed Coronal Mass Ejections (CMEs) were observed in the available coronagraph imagery in the last 24 hours. The greater than 10 MeV proton flux was below the 10 pfu threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours. The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was below the 1000 pfu threshold in the last 24 hours. The greater than 2 MeV electron flux is expected to be below the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours.

Geomagnetic conditions globally were mostly at quiet to unsettled levels (NOAA Kp 2 to 3). Locally, geomagnetic conditions were mostly at quiet to unsettled levels (K BEL 2 to 3), with an interval of active conditions (K BEL 4) between 19:00 UTC and 21:00 UTC on December 13. Mostly quiet to unsettled conditions are expected globally and locally over the next 24 hours, with possible isolated active conditions (NOAA Kp 4, K BEL 4), due to the continued influence of the high-speed stream. Over the past 24 hours, solar wind parameters (ACE) were enhanced, most likely due to the influence of the high-speed stream from the negative polarity coronal hole (SIDC Coronal Hole 142). Speed values ranged between 480 km/s and 690 km/s. The interplanetary magnetic field values varied between 2 nT and 14 nT. The Bz component varied between -5 nT and 10 nT. The interplanetary magnetic field angle was mostly in the negative sector. Enhanced solar wind conditions are expected to persist over the next 24 hours due to the continued influence of the high-speed stream.