Viewing archive of Thursday, 2 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 02 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Moderate (ISES: Major) magstorm expected (A>=50 or K=6)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
02 Oct 2025	179	032
03 Oct 2025	177	035
04 Oct 2025	175	011

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been moderate, with two M-class flares and a few C-class flares. The strongest flares were two M1.2 flares. The first one was SIDC Flare 5652, peaking at 16:50 UTC on October 01, associated with SIDC Sunspot Group 653 (NOAA Active Region 4232, magnetic type beta-gamma-delta). The second one was SIDC Flare 5654, peaking at 02:09 UTC on October 02, associated with SIDC Sunspot Group 592 (NOAA Active Region 4226, magnetic type beta). There are currently nine numbered active regions on the solar disk. The most complex is SIDC Sunspot Group 653 (magnetic type beta-gamma- delta). SIDC Sunspot Group 592 is currently rotating across the west limb. The solar flaring activity is expected to be moderate to high over the next 24 hours, with M-class flares very likely and a small chance for X-class flares.

Coronal mass ejections

A wide Coronal Mass Ejection (SIDC CME 567) was observed in LASCO/C2 and LASCO/C3 coronagraph imagery, lifting off the southwest quadrant around 10:30 UTC on October 01. It is most likely associated with eruptive activity near SIDC Sunspot Groups 648 and 659 (NOAA Active Regions 4230 and 4238). It is not expected to impact Earth. A second wide, slow Coronal Mass Ejection (SIDC CME 568) was observed in LASCO/C2 coronagraph imagery, lifting off the southwest quadrant around 03:00 UTC on October 02. It is most likely associated with the M1.2 flare (SIDC Flare 5654) that peaked at 02:09 UTC on October 02, associated with SIDC Sunspot Group 592 (NOAA Active Region 4226). 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 two equatorial, positive polarity coronal holes (SIDC Coronal Holes 128 and 123) are crossing the central meridian since September 29 and September 30 respectively.

Solar wind

The solar wind conditions (ACE) were enhanced during the last 24 hours, under the ongoing influence of a high-speed stream from the two equatorial, positive polarity coronal holes (SIDC Coronal Holes 128 and 123). The solar wind speed increased from 700 to around 840 km/s. The interplanetary magnetic field values were between 7 nT and 11 nT. The Bz component ranged between -9 nT and 6 nT. The interplanetary magnetic field angle phi was predominantly in the positive sector. Enhanced solar wind conditions are expected over the next 24 hours, mainly under the ongoing influence of the high-speed stream from SIDC Coronal Holes 128 and 123, with a small chance for the arrival of a glancing blow associated with SIDC CME 565 that lifted off at 09:45 on September 30.

Geomagnetism

Geomagnetic conditions globally during the last 24 hours were initially mostly at moderate storm levels (NOAA Kp 6- to 6), escalating to major storm levels (NOAA Kp 7-) between 03:00 UTC and 06:00 UTC on October 02. Geomagnetic conditions globally are currently at minor storm levels (NOAA Kp 5-). Geomagnetic conditions locally during the last 24 hours were initially at minor storm levels (K Bel 5), escalating to moderate storm levels (K Bel 6) between 07:00 UTC and 08:00 UTC on October 02. Geomagnetic conditions locally are currently at active levels (K Bel 4). The geomagnetic storms were the result of the ongoing influence of a high-speed stream from the two equatorial, positive polarity coronal holes (SIDC Coronal Holes 128 and 123. Mostly active to minor storm conditions (NOAA Kp 4 to 5), with possible isolated moderate storm intervals (NOAA Kp 6), are expected over the next 24 hours, under the ongoing influence of the high- speed stream from SIDC Coronal Holes 128 and 123, with a small chance for the arrival of a glancing blow associated with SIDC CME 565 that lifted off at 09:45 on September 30.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu threshold over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours, pending no eruptive activity from SIDC Sunspot Groups 592, 648 and 659 (NOAA Active Regions 4226, 4230 and 4238).

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 has been above the 1000 pfu threshold since 14:00 UTC on October 01. It is expected to remain above the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence is presently at moderate levels and is expected to increase over the next 24 hours.

Today's estimated international sunspot number (ISN): 164, based on 14 stations.

Solar indices for 01 Oct 2025

Wolf number Catania	///
10cm solar flux	184
AK Chambon La Forêt	060
AK Wingst	044
Estimated Ap	048
Estimated international sunspot number	168 - Based on 26 stations

Noticeable events summary

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

All times in UTC

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