Viewing archive of Tuesday, 26 August 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Aug 26 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

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

	10cm flux	Ap
26 Aug 2025	175	020
27 Aug 2025	180	016
28 Aug 2025	182	007

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with 4 M-class flares identified. The largest flare was a M4.5 flare (SIDC Flare 5237) peaking on August 26 at 05:25 UTC, which was produced by SIDC Sunspot Group 614 (NOAA Active Region 4197). That region and SIDC Sunspot Group 617 (NOAA Active Region 4199), both located close to the east limb, are driving most of the activity. Solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares likely and a small chance for X-class flares.

Coronal mass ejections

No Earth-directed Coronal Mass Ejections (CMEs) have been observed in the last 24 hours.

Coronal holes

SIDC Coronal Hole 126 (northern mid-latitude coronal hole with negative polarity) is located in the western hemisphere and its related high speed solar wind stream may arrive to the Earth in the next 24 hours.

Solar wind

The Earth is inside slow solar wind with speeds around 400 km/s and interplanetary magnetic fields of about 5 nT (directed towards the Sun, negative polarity). A high speed solar wind stream is expected to arrive in the next 24 hours, with probably only mild effects.

Geomagnetism

Geomagnetic conditions have been quiet to unsettled (Kp and B_Bel between 0 and 3). Similar conditions are expected until the arrival of the high speed solar wind stream in the next 24 hours (mostly active conditions expected then).

Proton flux levels

The greater than 10 MeV proton flux has continued to increase slowly and has almost reached the 10 pfu threshold, without going above it (currently at 9 pfu). A warning condition forecast is issued for the next 48 hours.

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 (except for a minimal crossing of the threshold between 13:00 and 26:00 UTC on 25 August, in GOES 19), 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): 184, based on 23 stations.

Solar indices for 25 Aug 2025

Wolf number Catania	125
10cm solar flux	175
AK Chambon La Forêt	016
AK Wingst	011
Estimated Ap	009
Estimated international sunspot number	139 - Based on 32 stations

Noticeable events summary

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

All times in UTC

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