Viewing archive of Friday, 12 September 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Sep 12 1257 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
12 Sep 2025	114	008
13 Sep 2025	112	017
14 Sep 2025	111	023

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. The largest flare was a C7.6 flare (SIDC Flare 5471) peaking on September 11 at 15:21 UTC, which was produced by SIDC Sunspot Group 624 (NOAA Active Region 4207). During the flare, the source region (AR 4207) of the flare had beta configuration of its photospheric magnetic field. A total of 7 numbered sunspot groups were identified on the disk over the past 24 hours. Solar flaring activity is expected to be at low to moderate levels over the next 24 hours, possibly with few C-class flares and a low chance for M-class flares.

Coronal mass ejections

A faint coronal mass ejection (CME) was first observed in the SOHO/LASCO C2 images around 10:30 UTC on Sep 11. It has a projected width of about 100 deg. This CME is associated to a filament eruption in the S hemisphere of the Sun. Narrow CMEs related to this filament eruption were also observed prior to this CME. With the bulk of the mass strongly directed towards SW, this CME will miss Earth, but a glancing blow related to this CME may be possible on Sep 15-16. No other Earth-directed CMEs were detected in the available coronagraph observations during the last 24 hour.

Coronal holes

Recurrent negative polarity coronal hole (SIDC Coronal Hole 116), which spans from 10 S to 30 N, is still crossing the central meridian. The high speed streams originating from this coronal hole are expected to impact the Earth from Sep 13.

Solar wind

Earth is presently inside the slow solar wind regime. The solar wind speed ranged from 365 km/s to 450 km/s and the interplanetary magnetic field ranged from 5 nT to 9 nT. The North-South component (Bz) ranged between -6 and 5 nT. Slow solar wind conditions are expected to continue over the next 24 hours, unless the high speed stream from the SIDC Coronal Hole 116 (negative polarity), which started to cross the central meridian on Sep 10, arrives earlier at Earth.

Geomagnetism

Geomagnetic conditions were at quiet to unsettled conditions (NOAA Kp 1 to 3), both globally and locally during the past 24 hours. We expect quiet to active conditions (K 1 to 4) in the next 24 hours, unless the high speed stream from the SIDC Coronal Hole 116 (negative polarity), which started to cross the central meridian on Sep 10, arrives earlier at Earth.

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-19 and GOES-18 satellites, remained below the 1000 pfu threshold level during the last 24 hours. The electron flux may exceed the threshold level in the next 24 hours. The 24h electron fluence is presently at normal level, and it is expected to remain so in the next 24 hours.

Today's estimated international sunspot number (ISN): 052, based on 24 stations.

Solar indices for 11 Sep 2025

Wolf number Catania	104
10cm solar flux	115
AK Chambon La Forêt	009
AK Wingst	010
Estimated Ap	010
Estimated international sunspot number	089 - Based on 25 stations

Noticeable events summary

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

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