Viewing archive of Wednesday, 18 June 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Jun 18 1231 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
18 Jun 2025	137	018
19 Jun 2025	135	012
20 Jun 2025	137	006

Solar Active Regions and flaring

Solar flaring activity was at high levels over the past 24 hours. A total of 7 numbered sunspot groups were identified on the visible solar disk. SIDC Sunspot Group 523 (NOAA Active Region 4114) remains the largest and most complex active region. It is classified as magnetic type beta-gamma-delta and produced an impulsive X1.2 flare (SIDC Flare 4675) with peak time 21:49 UTC on June 17. SIDC Sunspot Group 522 (NOAA Active Region 4115) has shown some increase in complexity is now classified as magnetic type beta-gamma. Two new regions, SIDC Sunspot Group 526 and SIDC Sunspot Group 527, have rotated from over the east limb and are producing low levels of activity. SIDC Sunspot Group 520 (NOAA Active Region 4110) has rotated behind the west limb. The remaining active regions on the visible disk have been mostly simple and quiet. Solar flaring activity is expected to be moderate over the next 24 hours with C-class flares expected and likely M-class flares.

Coronal mass ejections

A slow partial halo coronal mass ejection (SIDC CME 522) has left the Sun around 03:36 UTC on June 18 as observed in SOHO/LASCO C2 data. The CME is related to an activity behind the west limb and no impact on Earth is expected. No Earth-directed CMEs have been identified in the available coronagraph imagery over the past 24 hours.

Coronal holes

A large positive polarity coronal hole (SIDC Coronal Hole 104) continues to reside on the central meridian. This is a mid-latitude southern coronal hole covering a large longitudinal range which first crossed the central meridian on June 11. A mild high speed stream emanating from it is expected to continue influencing the Earth over the next days.

Solar wind

Over the past 24 hours the solar wind parameters (ACE and DSCOVR) were under the continuous mild influence from a high speed stream. The interplanetary magnetic field (B) was slightly enhanced with a maximum value of 9.6 nT and a minimum Bz of -8 nT. The solar wind speed reached a maximum of 530 km/s. The B field phi angle was predominantly in the positive sector (directed away from the Sun). The solar wind conditions are expected to continue to be under a mild influence of a high speed stream over the next days. There are small chances for an influence from an interplanetary shock and a mild glancing blow arrival later on June 18.

Geomagnetism

The geomagnetic conditions over the past 24 hours were quiet to unsettled. Quiet to active geomagnetic conditions are expected for the next 24 hours with low chances for isolated minor storms in case of a possible mild glancing blow and/or shock arrival from two CMEs (SIDC CMEs 518 and 519) on June 15.

Proton flux levels

Over the past 24 hours the greater than 10 MeV GOES proton flux has been at nominal levels. The greater than 10 MeV GOES proton flux is expected to expected to remain at nominal levels, though some increase is possible in case of fast eruptive solar activity related to SIDC Sunspot Group 523 (NOAA Active Region 4114).

Electron fluxes at geostationary orbit

The greater than 10 MeV GOES 18 and GOES 19 electron fluxes briefly exceeded the 1000 pfu threshold over the last 24 hours and are expected to exceed the threshold again over the next 24 hours. The 24-hour electron fluence was at the border of nominal to moderate levels and is expected to remain so in the next 24 hours.

Today's estimated international sunspot number (ISN): 134, based on 26 stations.

Solar indices for 17 Jun 2025

Wolf number Catania	147
10cm solar flux	139
AK Chambon La Forêt	020
AK Wingst	010
Estimated Ap	011
Estimated international sunspot number	114 - Based on 27 stations

Noticeable events summary

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

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