Viewing archive of Monday, 18 August 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Aug 18 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
18 Aug 2025	117	005
19 Aug 2025	117	023
20 Aug 2025	115	022

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. The largest flare was a C3.3 flare (SIDC Flare 5166) peaking on August 17 at 19:58 UTC, which was produced by SIDC Sunspot Group 598 (NOAA Active Region 4180). A total of 6 numbered sunspot groups were identified on the disk over the past 24 hours, with only Alpha or Beta magnetic configuration. Solar flaring activity is expected to be low over the next 24 hours, with C-class flares likely and a small chance for M-class flares.

Coronal mass ejections

No new Earth-directed Coronal Mass Ejections (CMEs) have been detected in the available coronagraph images.

Coronal holes

The negative polarity mid-latitude SIDC Coronal hole 116 ( that first reached the central meridian on August 15) has finished its transit across the central meridian.

Solar wind

The solar wind at the Earth is slow, with speeds around 340 km/s and interplanetary magnetic field reaching a maximum of 10 nT with the Bz reaching a minimum value of -7 nT. The solar wind speed is expected to become enhanced on 18-19 August, due to the potential arrival of the high- speed stream (HSS) associated with the SIDC coronal hole 116.

Geomagnetism

Geomagnetic activity was quiet over the past 24 hours both globally and locally. In response to the expected arrival of high-speed stream associated with SIDC Coronal Hole 116, geomagnetic conditions are expected to reach active level on August 18-19.

Proton flux levels

The greater than 10 MeV proton flux remained below the 10 pfu threshold and is expected to remain so over the next days.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 remained above the 1000 pfu threshold. Electron flux levels are expected to fluctuate around the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence remains at moderate levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 059, based on 24 stations.

Solar indices for 17 Aug 2025

Wolf number Catania	///
10cm solar flux	117
AK Chambon La Forêt	006
AK Wingst	006
Estimated Ap	004
Estimated international sunspot number	083 - 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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