Viewing archive of Saturday, 27 December 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Dec 27 1301 UTC

SIDC Forecast

Solar flares

C-class flares expected, (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
27 Dec 2025	167	008
28 Dec 2025	165	007
29 Dec 2025	163	008

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with few C-class flares and 1 M-class flare identified. The largest flare was a M5.1 flare (SIDC Flare 6496) peaking on December 27 at 01:50 UTC, which was produced by SIDC Sunspot Group 745. A total of 11 numbered sunspot groups were identified on the disk over the past 24 hours. SIDC Sunspot Group 740 (NOAA Active Region 4321) is the most complex region with its Beta-Delta magnetic configuration. Solar flaring activity is expected to be low to moderate over the next 24 hours, with C-class flares expected and a chance for M-class flares.

Coronal mass ejections

A partial halo coronal mass ejection (CME) was first observed in LASCO-C2 images at 02:24 UTC on Dec 27. Further analysis is ongoing to estimate the potential Earth-directed components. No other Earth-directed CME were detected in the available coronagraph observations during the last 24 hour.

Solar wind

Over the past 24 hours, solar wind parameters continued to reflect the waning influence of a high-speed stream (HSSs) from the elongated, posiitve polarity, recurrent coronal hole (SIDC Coronal Hole 128) which started to cross the central meridian on Dec 20. The solar wind speed ranged from 460 km/s to 570 km/s. The interplanetary magnetic field ranged between 1 nT and 6 nT, and the North-South component (Bz) ranged betweeen -5 nT and 5 nT. In the next 24 hours, enhanced solar wind conditions are expected to continue with the waning influence of HSSs.

Geomagnetism

Geomagnetic conditions were globally and locally at quiet to unsettled conditions (NOAA Kp and K BEL 1 to 3) during the past 24 hours, it is expected to remain so for the next 24 hours.

Proton flux levels

The greater than 10 MeV GOES proton flux was below the threshold level over the past 24 hours and it is expected to remain so for 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 above the 1000 pfu threshold for most of the time during the past 24 hours. It was in response to the high speed streams (HSS) from the southern, positive polarity, recurrent coronal hole (SIDC Coronal Hole 128) which started to cross the central meridian from Dec 20. The electron flux is expected to remain above this alert level during most of the next period. The electron fluence was at moderate levels and is expected to remain so.

Today's estimated international sunspot number (ISN): 140, based on 13 stations.

Solar indices for 26 Dec 2025

Wolf number Catania	///
10cm solar flux	166
AK Chambon La Forêt	013
AK Wingst	008
Estimated Ap	007
Estimated international sunspot number	117 - Based on 15 stations

Noticeable events summary

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

All times in UTC

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