Viewing archive of Sunday, 5 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 05 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
05 Oct 2025	155	010
06 Oct 2025	150	014
07 Oct 2025	145	028

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been low, with a few C-class flares. The strongest flare was a C3.5 flare (SIDC Flare 5681) peaking at 17:52 UTC on October 04, associated with SIDC Sunspot Group 661 (NOAA Active Region 4241, magnetic type beta). There are currently nine numbered active regions on the solar disk. The most complex are SIDC Sunspot Groups 653 and 657 (NOAA Active Regions 4243 and 4236), both with magnetic type beta-gamma. SIDC Sunspot Group 648 (NOAA Active Region 4230) has rotated behind the west limb. SIDC Sunspot Group 665 (magnetic type beta) has rotated on disk from the east limb, in the southeast quadrant. The solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares probable and X-class flares unlikely.

Coronal mass ejections

A wide Coronal Mass Ejection (SIDC CME 574) was observed in LASCO/C2 and LASCO/C3 coronagraph imagery, lifting off the west limb starting from around 17:30 UTC on October 04. It is most likely associated with eruptive activity behind the west limb. It is not expected to impact Earth. A faint CME (SIDC CME 575) was observed in LASCO/C2 coronagraph imagery, lifting off the southeast limb around 18:15 UTC on October 04. It is most likely associated with a prominence eruption near east the limb. It is not expected to impact Earth. A narrow CME (SIDC CME 576) was observed in LASCO/C2 data, lifting off the northeast limb around 22:40 UTC on October 04. It is most likely associated with a filament eruption in the northeast quadrant. It is not expected to impact Earth. A wide CME (SIDC CME 577) was observed in LASCO/C2 coronagraph imagery, lifting off the west limb starting from 03:25 UTC on October 05. It is most likely associated with eruptive activity behind the west limb. It is not expected to impact Earth. No other Earth-directed CMEs were observed in the available coronagraph imagery over the last 24 hours.

Coronal holes

The equatorial, positive polarity coronal hole (SIDC Coronal Hole 123) is crossing the central meridian since September 30.

Solar wind

The solar wind conditions (ACE) were enhanced during the last 24 hours, under the waning influence of a high-speed stream from the two equatorial, positive polarity coronal holes (SIDC Coronal Holes 128 and 123). The solar wind speed decreased from around 660 km/s to around 460 km/s. The interplanetary magnetic field was around 5 nT. The Bz component ranged between -4 nT and 3 nT. The interplanetary magnetic field angle phi was predominantly in the positive sector. A gradual return to slow solar wind conditions is mostly expected over the next 24 hours, with further enhancements possible due to a small chance of a mild glancing blow arrival, associated with SIDC CME 570, which lifted of around 07:00 UTC on October 03.

Geomagnetism

Geomagnetic conditions globally during the last 24 hours were initially at active levels (NOAA Kp 4), gradually decreasing to mostly unsettled levels (NOAA Kp 3- to 3+). Geomagnetic conditions locally were mostly at unsettled levels (K Bel 3) during the last 24 hours, with an interval of active levels between 15:00 UTC and 16:00 UTC on October 04. Mostly unsettled to active conditions (NOAA Kp 3 to 4) are expected over the next 24 hours, under the waning influence of the high-speed stream from SIDC Coronal Holes 128 and 123. Minor storm conditions (NOAA Kp 5) are possible due to a small chance of a mild glancing blow arrival, associated with SIDC CME 570, which lifted off around 07:00 UTC on October 03.

Proton flux levels

The greater than 10 MeV proton flux increased but remained below the 10 pfu threshold over the past 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 and GOES 19 was above 1000 pfu threshold during the last 24 hours and it is expected to remain so over the next 24 hours. The 24-hour electron fluence is presently at high levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 147, based on 11 stations.

Solar indices for 04 Oct 2025

Wolf number Catania	///
10cm solar flux	158
AK Chambon La Forêt	026
AK Wingst	018
Estimated Ap	022
Estimated international sunspot number	159 - Based on 18 stations

Noticeable events summary

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

All times in UTC

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