Viewing archive of Friday, 15 August 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Aug 15 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
15 Aug 2025	130	007
16 Aug 2025	130	007
17 Aug 2025	130	007

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. A total of 13 numbered sunspot groups were observed on the solar disk. Several of the SIDC Sunspot Groups have Alpha magnetic configurations and did not produce any flaring activity. The most productive region was SIDC Sunspot Group 590 (NOAA Active Region 4172), currently located at N08W64, which has a Beta magnetic configuration and was stable over the past 24 hours. This region produced the largest flare, a C6.8 flare (SIDC Flare 5151), peaking on August 15 at 10:37 UTC. Solar flaring activity is expected to remain low over the next 24 hours, with C-class flares very likely and a small chance for M-class flares

Coronal mass ejections

No Earth-directed coronal mass ejections (CMEs) were observed over the past 24 hours. Only a very small number of minor CMEs were detected, none of which are expected to impact Earth.

Coronal holes

SIDC Coronal Hole 123 (equatorial, positive polarity) first reached the central meridian on August 6 and is now positioned on the western side of the Sun, having completed its transit across the central meridian. The recurring SIDC Coronal Hole 104 (polar-south, positive polarity) reached the central meridian yesterday, August 14. Additionally, SIDC Coronal Hole 116, a mid-latitude coronal hole with negative polarity, began transiting the central meridian today.

Solar wind

Over the past 24 hours, solar wind conditions have returned to a slow solar wind regime. The total interplanetary magnetic field (Bt) remained around 5 nT and 6 nT, while the southward component of the interplanetary magnetic field (Bz) was mostly negative, reaching up to -4.7 nT. Solar wind speed remained moderate, fluctuating between 400 and 500 km/s. Slow solar wind conditions are expected to persist and gradually decrease over the next 24 hours.

Geomagnetism

Geomagnetic activity was mostly quiet to unsettled over the past 24 hours, with NOAA Kp indices ranging from 2 to 3 and the Belgian K-index similarly between 2 and 3. Geomagnetic conditions are expected to remain predominantly quiet, with occasional unsettled periods.

Proton flux levels

Proton flux remained below 10 pfu over the past 24 hours. A slight enhancement cannot be fully excluded due to the number of sunspot groups on the solar disc but is considered unlikely.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 exceeded the 1000 pfu threshold in response to high- speed streams associated with SIDC Coronal Hole 123 observed over the past days. Electron flux levels are expected to fluctuate around the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence remained at moderate levels and is expected to return to normal levels over the next 24 hours.

Today's estimated international sunspot number (ISN): 145, based on 18 stations.

Solar indices for 14 Aug 2025

Wolf number Catania	///
10cm solar flux	130
AK Chambon La Forêt	015
AK Wingst	012
Estimated Ap	014
Estimated international sunspot number	170 - Based on 25 stations

Noticeable events summary

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

All times in UTC

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