Viewing archive of Thursday, 11 September 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Sep 11 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

Quiet

	10cm flux	Ap
11 Sep 2025	120	011
12 Sep 2025	119	013
13 Sep 2025	117	028

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 C1.5 flare peaking on September 11 at 06:26 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. SIDC Sunspot Group 631 (NOAA Active Region 4213) is the complex region with its beta-gamma magnetic configurations. Solar flaring activity is expected to be at low to moderate levels 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 (CME) were detected in the available coronagraph observations during last 24 hours.

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

Solar wind parameters are transitioning from fast to slow solar wind regime. The solar wind speed ranged between 410 km/s and 525 km/s. The North-South component (Bz) ranged between -7 and 6 nT. The interplanetary magnetic field has ranged from 6 nT to 8 nT. Slow solar wind conditions are expected in the next 24 hours.

Geomagnetism

Geomagnetic conditions were globally at quiet to active conditions (NOAA Kp 1 to 4). It was locally over Belgium at quiet to unsettled conditions (K BEL 2 to 3) during the past 24 hours. We expect quiet to active conditions (K 1 to 4) in 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

Over the past 24 hours, the greater than 2 MeV electron flux, as measured by GOES-18 satellite, exceeded above the 1000 pfu threshold level around 16:15 UTC on Sep 10 and finally dropped below the threshold around 01:45 UTC Sep 11. It was in response to the high solar wind speed associated with the SIDC Coronal Hole 123 (positive polarity) which crossed the central meridian during Sep 02-09. The greater than 2 MeV electron flux, as measured by GOES-19 satellite, remained below the threshold level. In the next 24 hours, the electron flux may exceed the threshold level again. 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): 089, based on 20 stations.

Solar indices for 10 Sep 2025

Wolf number Catania	109
10cm solar flux	119
AK Chambon La Forêt	017
AK Wingst	014
Estimated Ap	014
Estimated international sunspot number	092 - Based on 24 stations

Noticeable events summary

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

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