Viewing archive of Friday, 19 December 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Dec 19 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
19 Dec 2025	114	008
20 Dec 2025	112	007
21 Dec 2025	110	007

Solar Active Regions and flaring

Solar flaring activity during the last 24 hours has been low, with few C-class flares. The strongest flare was a C1.9 flare (SIDC Flare 6446), peaking at 05:43 UTC on December 19, associated with SIDC Sunspot Group 722 (NOAA Active Region 4307, magnetic type beta). There are currently seven numbered active regions on the solar disk. The most complex ones have a beta magnetic type. SIDC Sunspot Groups 720 and 722 (NOAA Active Regions 4305 and 4307) are currently rotating across the west limb. The solar flaring activity is expected to be low over the next 24 hours, with C-class flares very likely and a small chance for M-class flares.

Coronal mass ejections

No Earth-directed Coronal Mass Ejections (CMEs) were observed in the available coronagraph imagery during the last 24 hours.

Solar wind

The solar wind conditions (ACE) during the last 24 hours were enhanced, likely under the waning influence of high-speed streams from the north-south elongated, negative polarity coronal hole (SIDC Coronal Hole 136) and the southern, negative polarity coronal hole (SIDC Coronal Hole 137). The solar wind speed was initially around 600 km/s and has currently decreased to around 530 km/s. The interplanetary magnetic field values decreased from around 8 nT to around 4 nT. The Bz component was between -4 nT and 5 nT. The interplanetary magnetic field angle phi was mostly negative. A gradual return to the slow solar wind regime is expected over the next 24 hours, with some enhancements still possible under the waning influence of the high-speed stream from SIDC Coronal Holes 136 and 137.

Geomagnetism

Geomagnetic conditions globally were unsettled (NOAA Kp 3) between 15:00 UTC on December 18 and 00:00 UTC on December 19 and then decreased to quiet (NOAA Kp 2). Geomagnetic conditions locally reached active levels (K Bel 4) between 16:00 UTC and 20:00 UTC on December 18. Mostly quiet conditions (NOAA Kp 1 to 2) are expected over the next 24 hours, with a small chance of isolated unsettled intervals (NOAA Kp 3), under the waning influence of the high-speed stream from SIDC Coronal Holes 136 and 137.

Proton flux levels

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

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 was above the 1000 pfu threshold between 15:00 UTC and 23:45 UTC on December 18. The greater than 2 MeV electron flux measured by GOES 19 was above the 1000 pfu threshold between 12:00 UTC and 20:10 UTC on December 18, and has been above the threshold since 08:50 UTC on December 19. The greater than 2 MeV electron flux is expected to be above the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence was at moderate levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 051, based on 07 stations.

Solar indices for 18 Dec 2025

Wolf number Catania	///
10cm solar flux	116
AK Chambon La Forêt	022
AK Wingst	018
Estimated Ap	020
Estimated international sunspot number	065 - Based on 09 stations

Noticeable events summary

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

All times in UTC

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