Viewing archive of Tuesday, 28 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 28 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
28 Oct 2025	121	034
29 Oct 2025	121	067
30 Oct 2025	121	017

Solar Active Regions and flaring

Solar flaring activity was very low over the past 24 hours. The X-ray flux was below C level. A total of 7 numbered sunspot groups were identified on the disk over the past 24 hours. All the sunspot group have simple (alpha or beta) magentic field configuration. Solar flaring activity is expected to be low over the next 24 hours, with C-class flares likely.

Coronal mass ejections

There were two wide CME on 27 October, erupting towards the north. The first one at 08:12 UT and the second one at 13:21 UT, both CMEs are backsided and will not arrive to the Earth.

Coronal holes

SIDC Coronal Hole 123 (mid-latitude coronal hole with a positive polarity) crossed the central meridian on October 25.

Solar wind

Over the past 24 hours, solar wind parameters (ACE and DSCOVR) reflected a slow solar wind regime. Around 15:00 UT on 26 October we observed weak signatures of what could be the expected glancing blow from the CME on 23 October (SIDC CME 586), with the interplanetary magnetic field increasing to 11 nT. The speed has risen now to 430 km/s and the magnetic field is at 9 nT. In the next 24 hours, we expect the arrival of a high-speed stream from a large positive polarity coronal hole (SIDC Coronal Hole 123).

Geomagnetism

Geomagnetic conditions were mostly unsettled, reaching active levels locally (NOAA Kp: up to 3; K-Bel: up to 4). In the next 24 hours, the expected high-speed stream arrival from a large recurrent positive polarity coronal hole (SIDC Coronal Hole 123) may cause moderate storm levels.

Proton flux levels

The greater than 10 MeV GOES proton flux was below the 10 pfu threshold level over the past 24 hours and is expected to remain so for the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was below the 1000 pfu threshold. The greater than 2 MeV electron flux is expected to remain below the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence was at normal levels and is expected to be at normal levels over the next 24 hours.

Today's estimated international sunspot number (ISN): 106, based on 11 stations.

Solar indices for 27 Oct 2025

Wolf number Catania	087
10cm solar flux	121
AK Chambon La Forêt	017
AK Wingst	008
Estimated Ap	007
Estimated international sunspot number	096 - Based on 23 stations

Noticeable events summary

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

All times in UTC

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