Viewing archive of Thursday, 4 June 2026

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2026 Jun 04 1236 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Major (ISES: Severe) magstorm expected (A>=100 or K>=7)

Solar protons

Quiet

	10cm flux	Ap
04 Jun 2026	148	024
05 Jun 2026	150	123
06 Jun 2026	150	035

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours. There are currently 8 numbered regions on the disk. The largest flare was a C5.1 flare (SIDC Flare 7848) peaking on June 03 at 23:43 UTC, which was produced by SIDC Sunspot Group 887 (NOAA Active Region 4459). Sunspot Groups 886 and 887 (NOAA Active Region 4458 and 4459) continued to grow over the period and have magnetic type beta. Sunspot Group 860 (NOAA Active Region 4455) simplified slightly but remains the most complex region on the disk. Sunspot group 853 (NOAA Active Region 4444) has now rotated over the west limb and SIDC Sunspot group 873 and 888 (NOAA Active Regions 4460 and 4446) will rotate over the limb over the next hours. The remaining regions are simple and mostly quiet. Solar flaring activity is expected to be moderate over the next 24 hours, with C-class flares expected and M-class flares probable with a chance for X-class flares.

Coronal mass ejections

Multiple Coronal Mass Ejections (CMEs) reported yesterday are predicted to impact Earth. The eruptions on June 02, related to the on disk dimmings associated with the M1.2 and M3.3 flares (SIDC Flares 7825 and 7826), were not associated with clear CME signatures in the coronagraph data possibly due to the simultaneous CMEs near the limb. However, any CMEs associated with these events are expected to be caught by the following eruptions from June 03. Three CMEs were detected on June 03 with Earth directed components: Firstly, a halo CME, associated with the M9.3 flare (SIDC flare 7838), seen in SOHO LASCO-C2 and seen STEREO-A COR2 starting at June 03 at 01:53 UTC. Secondly, a partial halo CME (directed to the north-west), detected in SOHO LASCO-C2 from 07:58 UTC on June 03, associated with the M7.7 flare (SIDC flare 7840). Thirdly, a partial halo CME (directed to the north-west), detected in SOHO LASCO-C2 from 11:48 UTC on June 03, associated with the X1.0 flare (SIDC flare 7842). These CMEs are expected to impact Earth from late on June 04 and through June 05.

Solar wind

Over the past 24 hours, the solar wind parameters reflected generally slow solar wind conditions. The solar wind speed ranged between 400 and 450 km/s. The total magnetic field increased slightly to 11nT when the interplanetary magnetic field phi angle switched from the negative to the positive sector (directed away from the Sun) at around 19:30 UTC June 03. A large enhancement in the solar wind speed and magnetic field strength is expected on June 04 and June 05, due to the expected arrival of multiple CMEs which left the Sun on June 03.

Geomagnetism

The geomagnetic conditions were at quiet to unsettled levels globally and locally (NOAA Kp and K Bel 1-3). Moderate to major storm conditions are expected from late on June 04 with severe storm intervals possible, due to the anticipated combined CME arrivals.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu threshold over the past 24 hours. It is expected to remain below this threshold level over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-19, was above the 1000 pfu threshold and reached a maximum value of 2334. The greater than 2 MeV electron flux is expected to be elevated and just above this threshold over the next 24 hours. The electron fluence was at normal levels and is expected to be at normal levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 148, based on 12 stations.

Solar indices for 03 Jun 2026

Wolf number Catania	///
10cm solar flux	147
AK Chambon La Forêt	017
AK Wingst	014
Estimated Ap	013
Estimated international sunspot number	142 - 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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