Daily bulletin on solar and geomagnetic activity from the SIDC

Datum av rapporten: 2026 Apr 02 1342 UTC

SIDC Forecast

Solutbrott

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

Geomagnetism

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

Diagram över protonflöde

Quiet

	10cm flux	Ap
02 Apr 2026	132	024
03 Apr 2026	128	017
04 Apr 2026	124	017

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares observed. The largest event was a C8.1 flare (SIDC Flare 7303), peaking on 01 April at 19:58 UTC, originating from SIDC Sunspot Group 838 (NOAA Active Region 4409). This region was the main contributor to the observed flaring activity, producing multiple C-class events. Additional C-class flares were also observed from SIDC Sunspot Group 832 (NOAA Active Region 4403) and SIDC Sunspot Group 830 (NOAA Active Region 4401). A total of nine numbered sunspot groups were present on the solar disk. Most regions exhibited simple Alpha magnetic configurations and were stable or in decay. SIDC Sunspot Group 835 (NOAA Active Region 4404) showed a Beta magnetic configuration, while SIDC Sunspot Group 836 (NOAA Active Region 4405), currently located at approximately S27E05, exhibited a Beta-Gamma magnetic configuration and remains the most complex region on the disk. Solar flaring activity is expected to remain low over the next 24 hours, with C-class flares very likely and a chance for isolated M-class flares, primarily from SIDC Sunspot Group 836 (NOAA Active Region 4405) and SIDC Sunspot Group 838 (NOAA Active Region 4409).

Koronamassutkastning

No coronal mass ejections were detected in available coronagraph imagery over the past 24 hours.

Koronal hål

SIDC Coronal Hole 149, an equatorial coronal hole with negative polarity, is now well positioned on the western side of the solar disk after crossing the central meridian on 30 March. SIDC Coronal Hole 142, a returning mid-latitude coronal hole with negative polarity, is now further visible on the eastern side of the solar disk following its rotation over the east limb.

Solvind

Solar wind parameters were at slow to moderately enhanced levels over the past 24 hours, followed by a clear transition to strongly disturbed conditions. Solar wind speed increased from about 400-450 km/s to values between approximately 600 and 660 km/s. The interplanetary magnetic field (IMF) was significantly enhanced, with the total field (Bt) reaching up to about 17 nT. The Bz component showed strong variability, with sustained southward intervals reaching down to approximately -15 nT. In addition, the phi angle rotated from a positive (away) to a negative (towards) sector, indicating the arrival of a high-speed solar wind stream associated with SIDC Coronal Hole 149 (an equatorial coronal hole with negative polarity that reached the central meridian on 30 March). These observations indicate ongoing ICME passage followed by the onset of high- speed stream conditions. Solar wind conditions are expected to remain disturbed over the next 24 hours due to continued high-speed stream influence.

Geomagnetism

Geomagnetic conditions ranged from unsettled to active over the past 24 hours, with storm levels reached. The global NOAA Kp index peaked at 5, while the local K index (Belgium) reached active levels (up to K=3). The enhanced geomagnetic activity was driven by the arrival of the high-speed solar wind stream associated with SIDC Coronal Hole 149, combined with sustained periods of southward interplanetary magnetic field (negative Bz). Geomagnetic conditions are expected to remain active to storm levels over the next 24 hours due to continued disturbed solar wind conditions.

Proton flux levels

The greater than 10 MeV proton flux remained at background levels over the past 24 hours, with no proton event observed. All measured energy channels remained well below the event threshold. The greater than 10 MeV proton flux is expected to remain at background levels over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux was at moderate levels at the beginning of the period, followed by a sharp decrease around 02 April 01:00 UTC, dropping to low levels. This decrease is consistent with the geomagnetic storm conditions (Kp 5) and associated magnetospheric depletion. The 24-hour fluence remained at moderate levels. Electron fluxes are expected to remain below the high flux threshold in the short term. An increase to high levels is expected in the coming 2-3 days due to the arrival of the high-speed solar wind stream associated with SIDC Coronal Hole 149, which may lead to enhanced electron acceleration at GEO. The fluence is expected to increase accordingly.

Today's estimated international sunspot number (ISN): 151, based on 10 stations.

Solar indices for 01 Apr 2026

Wolf number Catania	134
10cm solar flux	142
AK Chambon La Forêt	018
AK Wingst	010
Estimated Ap	010
Estimated international sunspot number	136 - Based on 15 stations

Noticeable events summary

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