Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2026 Mar 31 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
31 Mar 2026	149	039
01 Apr 2026	145	017
02 Apr 2026	142	012

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 C2.1 flare (SIDC Flare 7293), peaking on 30 March at 20:47 UTC, originating from SIDC Sunspot Group 831 (NOAA Active Region 4402). Additional C-class flares were mainly produced by SIDC Sunspot Group 836 (NOAA Active Region 4405) and SIDC Sunspot Group 837 (NOAA Active Region 4407). A total of ten numbered sunspot groups were present on the solar disk. Most regions were simple and stable or in decay, with Alpha or Beta magnetic configurations. SIDC Sunspot Group 836 (NOAA Active Region 4405), currently located at approximately S27E27, remained the most relevant region on the disk, showing continued growth and a Beta magnetic configuration. 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).

Coronal mass ejections

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

Coronal holes

SIDC Coronal Hole 149, an equatorial coronal hole with negative polarity, reached the central meridian on 30 March and is currently still transiting it. This coronal hole previously crossed the central meridian on 04 March.

Solar wind

olar wind parameters were at slow to moderately enhanced levels over the past 24 hours. Solar wind speed ranged between approximately 400 and 510 km/s. The interplanetary magnetic field (IMF) was at moderate levels, with the total field (Bt) varying between about 3 and 9 nT. The southward IMF component (Bz) showed variable conditions, with alternating northward and southward intervals, including several negative excursions reaching approximately -7 nT. Solar wind conditions are expected to become disturbed over the next 24 hours due to the anticipated arrival of the interplanetary coronal mass ejection (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). This may result in enhanced and more complex solar wind conditions.

Geomagnetism

Geomagnetic conditions were quiet to unsettled over the past 24 hours, with the global NOAA Kp index reaching up to 3 and local K indices (Belgium) remaining at quiet to unsettled levels. Geomagnetic conditions are expected to become active to storm levels (up to 6-7). over the next 24 hours due to the anticipated arrival of the interplanetary coronal mass ejection (SIDC CME 644).

Proton flux levels

The greater than 10 MeV proton flux remained at background levels over the past 24 hours. No proton event was observed. 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 occasional fluctuations. The 24-hour fluence remained at normal level. 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 normal level.

Today's estimated international sunspot number (ISN): 142, based on 14 stations.

Solar indices for 30 Mar 2026

Wolf number Catania	///
10cm solar flux	152
AK Chambon La Forêt	013
AK Wingst	011
Estimated Ap	011
Estimated international sunspot number	145 - Based on 23 stations

Noticeable events summary

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