Viewing archive of Wednesday, 27 August 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Aug 27 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Proton event expected (10 pfu at >10 MeV)

	10cm flux	Ap
27 Aug 2025	202	007
28 Aug 2025	202	007
29 Aug 2025	202	007

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with 1 M-class flare identified. This was an M1.0 flare (SIDC Flare 5239) peaking on August 26 at 14:07 UTC, which was produced by SIDC Sunspot Group 592 (NOAA Active Regions 4202). A total of 14 numbered sunspot groups were identified on the disk over the past 24 hours. Solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares likely.

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, its associated high speed stream may still reach the Earth today.

Solar wind

The Earth is inside slow solar wind with speeds around 350 km/s and interplanetary magnetic fields of about 7 nT (directed towards the Sun, negative polarity). The high speed stream from SIDC Coronal Hole 126 has not arrived to the Earth, it may still do so today (with minor influence expected).

Geomagnetism

Geomagnetic conditions have been quiet (Kp and B_Bel between 0 and 2). Quiet to unsettled periods are expected for the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux passed above the 10 pfu threshold on 26 August, and is currently at 12 pfu. The proton levels started to slowly increase on 22 August (as the result of a backsided CME on 21 August) and have gradually approached the threshold. Since 25 August the levels were very close to the 10 pfu mark. The flux will remain elevated in the next 24 hours, but no strong additional increases are expected.

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): 199, based on 12 stations.

Solar indices for 26 Aug 2025

Wolf number Catania	172
10cm solar flux	202
AK Chambon La Forêt	011
AK Wingst	008
Estimated Ap	009
Estimated international sunspot number	187 - 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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