Viewing archive of Sunday, 5 April 2026

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2026 Apr 05 1244 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
05 Apr 2026	126	007
06 Apr 2026	122	007
07 Apr 2026	120	007

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with one M-class flare observed. The largest event was an M1.0 flare (SIDC Flare 7346), peaking on 04 April at 23:04 UTC, originating from SIDC Sunspot Group 838 (NOAA Active Region 4409). Several C-class flares were also recorded, with sustained activity primarily produced by SIDC Sunspot Group 838. Additional low-level activity was observed from the newly emerged SIDC Sunspot Group 840. A total of seven numbered sunspot groups were present on the solar disk. Most regions exhibited simple Alpha or Beta magnetic configurations and remained stable. SIDC Sunspot Group 838 (NOAA Active Region 4409), currently located near N01W19, maintained a Beta-Gamma-Delta magnetic configuration and continued to dominate solar activity, although signs of slight decay in its structure were noted. A new region, SIDC Sunspot Group 840, located near N10E18, exhibited a Beta magnetic configuration and showed growth, producing several C-class flares. Solar flaring activity is expected to decrease to low levels over the next 24 hours, with C-class flares very likely and a chance for isolated M-class flares, primarily from SIDC Sunspot Group 838 (NOAA Active Region 4409).

Coronal mass ejections

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

Coronal holes

The SIDC Coronal Hole 149 (equatorial coronal hole with negative polarity) is positioned on the western side of the solar disk after crossing the central meridian on 30 March. Its associated high-speed solar wind stream is currently influencing near-Earth solar wind conditions. The SIDC Coronal Hole 142 (high-latitude coronal hole with a negative polarity) first reached the central meridian on April 03 and is now positioned on the western side of the Sun.

Solar wind

Solar wind parameters were at moderately enhanced levels over the past 24 hours. Solar wind speed gradually decreased from around 650 km/s to approximately 500–550 km/s. The interplanetary magnetic field (IMF) was weak to moderate, with the total field (Bt) generally ranging between about 2 and 6 nT. The Bz component showed variable conditions, with brief southward intervals reaching approximately -5 nT. These conditions are consistent with the waning influence of the high-speed solar wind stream associated with SIDC Coronal Hole 149. Solar wind conditions are expected to remain slightly enhanced over the next 24 hours, with a continued gradual decline in speed and variable IMF conditions. Following this, in about 1-2 days, a weak influence from the high-speed stream associated with SIDC Coronal Hole 142 (a high-latitude coronal hole with negative polarity that crossed the central meridian on 03 April) is expected. However, as this stream did not produce significant enhancements (solar wind speed remaining below about 550 km/s), only a minor impact on near-Earth solar wind conditions is expected.

Geomagnetism

Geomagnetic conditions were mostly quiet to unsettled over the past 24 hours, with occasional active intervals. The global NOAA Kp index reached up to 4, while the local K index (Belgium) reached up to K=4 (active levels). Activity was primarily driven by residual high-speed solar wind stream influence combined with intermittent southward interplanetary magnetic field (IMF) conditions. Geomagnetic conditions are expected to remain mostly quiet to unsettled, with possible isolated active periods over the next 24 hours depending on the IMF Bz variability.

Proton flux levels

The greater than 10 MeV proton flux remained below the event threshold (10 pfu) over the past 24 hours. Fluxes showed a gradual declining trend from previously elevated levels, with values generally below 5–6 pfu and decreasing towards near-background levels by the end of the period. Higher energy channels (greater than 100 MeV and greater than 500 MeV) remained at background levels throughout. STEREO-A measurements also indicate elevated but decreasing proton flux, supporting a weak and likely far-sided source. The greater than 10 MeV proton flux is expected to remain below the event threshold over the next 24 hours, with continued gradual decline and only minor variations possible.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux remained at moderate to high levels over the past 24 hours. A temporary dropout to low levels was observed around 05 April around 03:00 UTC. The 24-hour fluence was at moderate to high levels. Electron fluxes are expected to remain moderate to high over the next 24-48 hours, with possible further enhancements due to the ongoing influence of high-speed solar wind stream conditions.

Today's estimated international sunspot number (ISN): 103, based on 11 stations.

Solar indices for 04 Apr 2026

Wolf number Catania	///
10cm solar flux	128
AK Chambon La Forêt	023
AK Wingst	016
Estimated Ap	016
Estimated international sunspot number	116 - Based on 18 stations

Noticeable events summary

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

All times in UTC

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