Viewing archive of Sunday, 31 August 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Aug 31 1232 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
31 Aug 2025	222	007
01 Sep 2025	222	060
02 Sep 2025	222	023

Solar Active Regions and flaring

A total of 10 numbered sunspot groups were identified on the disk over the past 24 hours. Three M-class flares were detected in the last 24 hours. The largest flare was a M2.7 flare (SIDC Flare 5391) peaking on August 30 at 20:02 UTC, which was produced by SIDC Sunspot Group 617 (NOAA Active Region 4199). Solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares possible and a chance for X-class flares.

Coronal mass ejections

A halo CME erupted on 30 August, first seen at 20:12 UT on SOHO LASCO C2. The CME was associated with an M2.7 flare from SIDC Sunspot Group 617 (NOAA 4199), located at N04E01 (almost at disk center). This CME is Earth directed, preliminary speeds calculation estimates are about 1600 km/s, with an arrival time around 14:00 UT on 1 September. These values may be updated in the coming hours as the result of ongoing analysis.

Coronal holes

SIDC Coronal Hole 122 (equatorial coronal hole with a negative polarity) is in the western hemisphere and its associated high speed solar wind is expected today.

Solar wind

The solar wind speed is starting to increase (currently at 450 km/s) as a result of the expected arrival from the high speed solar wind from SIDC Coronal Hole 122. This is a narrow coronal hole, so the associated high speed stream in the coming hours is expected to be short and mild in terms of speed.

Geomagnetism

Geomagnetic conditions have been quiet to unsettled (Kp and K_Bel between 0 and 3). Active conditions can be expected for today and up to major storm conditions tomorrow when the CME from 30 August is expected to arrive.

Proton flux levels

The greater than 10 MeV proton flux has been below the 10 pfu threshold in the last 24 hours. It is expected to remain at nominal levels.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux as measured by GOES 18 and 19 remained below the 1000 pfu alert threshold, similar conditions expected for the next 24 hours. The 24 h electron fluence was at normal levels and is expected to remain so.

Today's estimated international sunspot number (ISN): 196, based on 17 stations.

Solar indices for 30 Aug 2025

Wolf number Catania	///
10cm solar flux	317
AK Chambon La Forêt	014
AK Wingst	006
Estimated Ap	007
Estimated international sunspot number	196 - Based on 24 stations

Noticeable events summary

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

All times in UTC

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