Viewing archive of Monday, 29 December 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Dec 29 1240 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
29 Dec 2025	195	010
30 Dec 2025	203	017
31 Dec 2025	210	038

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with 4 M-class flares recorded. The largest flare was an M4.2 flare (SIDC Flare 6518) peaking on December 28 at 22:39 UTC, which was produced by SIDC Sunspot Group 735 (NOAA Active Region 4317). SIDC Sunspot Groups 744 and 745 (NOAA Active Regions 4324 and 4325, respectively) are two of the other complex regions on disk (Beta-Gamma) and both also produced low level M-class flares and were growing over the period. SIDC Sunspot Group 740 (NOAA Active Region 4321, magnetic type Beta Delta) was quiet and is now approaching the west solar limb. The remaining regions are simple and mostly quiet. Solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares expected and a chance for X-class flares.

Coronal mass ejections

A partial halo Coronal Mass Ejection (CME) directed to the north-west, with a width of approximately 120 degrees and speed of around 450 km/s, was detected in LASCO-C2 data from 23:00 UTC on December 28. This CME (SIDC CME 616) was associated with an M4.2 flare (SIDC Flare 6518) peaking on December 28 at 22:39 UTC, which was produced by SIDC Sunspot Group 735 (NOAA Active Region 4317). This CME is currently being modelled, but initial analysis suggests this would likely have a glancing blow arrival at Earth early on January 01. No other Earth-directed (CMEs) were observed in the available coronagraph imagery.

Coronal holes

SIDC Coronal Hole 140 (mid-latitude, negative polarity) continues to transit the central meridian since December 28.

Solar wind

Over the past 24 hours, solar wind parameters reflected a slow solar wind regime. The solar wind speed decreased from 480 km/s to around 415 km/s. The interplanetary magnetic field ranged between 3 and 8 nT, and Bz had a minimum of -5nT. The interplanetary magnetic field angle phi was mostly in the positive sector. Slow solar wind conditions are expected to continue for the next 24 hours. From late on December 30, enhanced solar wind conditions are possible due the CIR and high speed stream arrival associated with SIDC Coronal Hole 140 (negative polarity) which began to cross the central meridian on December 28.

Geomagnetism

Geomagnetic conditions were at quiet to unsettled levels globally (NOAA Kp 1 to 3) and locally (K BEL 1 to 3) over the past 24 hours. Quiet to unsettled conditions are expected for the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu threshold over the past 24 hours. It is expected to remain below this threshold level over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-18 and GOES-19 satellites, was mostly above the 1000 pfu threshold for past 24 hours. The greater than 2 MeV electron flux is expected to again exceed the 1000 pfu threshold over the next 24 hours. The electron fluence was at moderate levels and is expected to remain so.

Today's estimated international sunspot number (ISN): 141, based on 08 stations.

Solar indices for 28 Dec 2025

Wolf number Catania	///
10cm solar flux	188
AK Chambon La Forêt	019
AK Wingst	010
Estimated Ap	009
Estimated international sunspot number	152 - Based on 22 stations

Noticeable events summary

Provided by the Solar Influences Data analysis Center© - SIDC - Processed by SpaceWeatherLive

All times in UTC

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