Daily bulletin on solar and geomagnetic activity from the SIDC

Emès: 2026 Apr 01 1232 UTC

SIDC Forecast

Erupcions solars

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

Geomagnetism

Moderate (ISES: Major) magstorm expected (A>=50 or K=6)

Protons solars

Quiet

	10cm flux	Ap
01 Apr 2026	135	029
02 Apr 2026	130	017
03 Apr 2026	127	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 C1.2 flare (SIDC Flare 7295), peaking on 01 April at 06:51 UTC, originating from SIDC Sunspot Group 838 (NOAA Active Region 4409). Multiple C-class flares were also produced by SIDC Sunspot Group 836 (NOAA Active Region 4405), which remained the most active region on the disk. A total of nine numbered sunspot groups were present on the solar disk. Most regions exhibited simple magnetic configurations and were either stable or in decay. 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, mainly from SIDC Sunspot Group 836 (NOAA Active Region 4405) and SIDC Sunspot Group 838 (NOAA Active Region 4409).

Expulsions de masses coronals

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

Forats coronals

The SIDC Coronal Hole 149 (an equatorial coronal hole with negative polarity) that reached the central meridian on 30 March is now located on the western side of the solar disk. SIDC Coronal Hole 142, a returning mid-latitude coronal hole with negative polarity, has rotated over the east limb and is now visible on the eastern side of the solar disk.

Vent solar

Solar wind parameters were at slow solar wind conditions over the past 24 hours. Solar wind speed gradually decreased from about 450 km/s to approximately 350 km/s. The interplanetary magnetic field (IMF) remained at low to moderate levels, with the total field (Bt) ranging between about 2 and 7 nT. The southward IMF component (Bz) component showed variable conditions, fluctuating between northward and southward orientations, with several southward excursions reaching approximately -4 nT. Over the last 30 minutes, an increase in solar wind activity has been observed, with Bt (up to around 16 nT) and Bz showing enhanced variability and solar wind speed increasing up to approximately 510 km/s. This may indicate the beginning of the onset of a solar wind disturbance associated with the anticipated interplanetary coronal mass ejection (SIDC CME 644). Solar wind conditions are expected to become further disturbed over the next 24 hours due to the anticipated arrival of the interplanetary CME (SIDC CME 644) associated with the X1.4 flare (SIDC Flare 7290), possibly combined with or followed by the high-speed solar wind stream originating from the equatorial coronal hole (SIDC Coronal Hole 149, negative polarity).

Geomagnetism

Geomagnetic conditions were quiet to unsettled over the past 24 hours, with the global NOAA Kp index reaching up to 3. The local K index (Belgium) ranged between 1 (quiet) and 3 (unsettled), with a brief interval reaching 4 (active). Geomagnetic conditions are expected to become active to storm levels over the next 24 hours due to the anticipated arrival of the interplanetary coronal mass ejection (SIDC CME 644). Moderate geomagnetic storm conditions are likely (K up to 6), with a chance of stronger activity, particularly if periods of southward interplanetary magnetic field (IMF) orientation (negative Bz).

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 remained at normal to moderate levels over the past 24 hours, with values generally below the high flux threshold and a decreasing trend towards the end of the period. The 24-hour fluence remained at moderate levels. Electron fluxes are expected to remain at normal to moderate levels over the next 24 hours, with a possibility of increasing to high levels in the coming days due to the anticipated arrival of a high-speed solar wind stream. The fluence is expected to remain at moderate levels.

Today's estimated international sunspot number (ISN): 135, based on 12 stations.

Solar indices for 31 Mar 2026

Wolf number Catania	///
10cm solar flux	141
AK Chambon La Forêt	013
AK Wingst	006
Estimated Ap	006
Estimated international sunspot number	135 - Based on 28 stations

Noticeable events summary

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