Update 2026-04-04 0930z
Active sun with numerous filament eruptions, M-class flares and fast solar wind from a rectangular coronal hole – more flares possible
Synoptics
2026-04-04 0530z – The coronal hole west of the centre has an almost rectangular shape. It is negatively polarised and located mainly south of the equator. We can regard it as the old magnetic south pole of the current solar cycle 25. Around it are active regions, to the north the new negative polar coronal hole and at the south pole the new positive polar coronal hole of the next solar cycle 26.
The bands of the new cycle move towards the equator and compress the old cycle with its twisted magnetic fields – resulting in an increase in solar activity.
- Region 4405 produced an X-flare and a large CME that narrowly missed us. Since then, the region has been quiet and decaying. However, a large sigmoid-shaped core filament is still waiting for the signal to erupt.
- Region 4409 shows rapid development and increasing complexity, the flares it produces are getting stronger and stronger, most recently an M7.5 flare, but probably without significant coronal mass ejection (CME)
- Region 4403 was associated with a large filament that erupted with a C6 flare and opened the northern coronal hole, the shock front of the CME arrived around 1500z on 3 April
- Region 4404 produced a M3.6 flare at around 1800z on 2 April, a CME of smaller size was created, it could possibly graze us on 5 April
The high-speed stream from coronal hole CH36- is very geoeffective, together with grazing CMEs or their shock fronts the indices for geomagnetic storms reached Hp30 index 7+, and Kp index 7-, i.e. G3 STRONG STORM from 1500-1800z on 4.4. The plasma velocity near the Earth reached peak values of 858 km/s on 3.4.
The influence of the coronal hole will slowly diminish; if the CME of 2 April grazes us on 5 April, there could again be increased geomagnetic activity, perhaps episodes with G1 MINOR STORM or G2 MODERATE STORM, but the trend is decreasing – substorms are still possible.
The timing of the previous impacts was unfavourable for Europe. In addition, the bright moon makes aurora sightings more difficult. So far there have only been reports from Central Europe for 1 April and 2 April.
Solar wind analysis
Correction: The high-speed stream comes from CH36- not CH34- (CH = coronal hole)
The shock from the CME on 30 March (associated with X1.4 flare from region 4405) reached us later than expected on 1 April. Below we see mixed characteristics of a stream interaction region/high-speed stream and a CME passing nearby. In the ongoing high-speed stream, the shock front of the CME reached us from the vicinity of 4403 (filament eruption with C6 flare). We will probably not see the core of the CME.
- Auroral sightings in the AKM forum: Polarlicht 2026-04-02 (night of 1.4./2.4.)
- Article on the X1.4 flare here: X1.4 Flare and CME (’solar storm‘) with earth-directed components
Filament eruptions
The flying toilet seat from 1.4.2026, 1800z
SDO AIA 304, 171, 193, 211
A ring-shaped filament had formed around the otherwise simple region 4399. Such a configuration is unstable and often leads to eruptions. A rather slow CME to the south-west was produced.
The circus tent from 1.4.2026, 2300z
An astonishing filament eruption in several respects from the vicinity of region 4403.
Two intertwined filaments. One pulls the other upwards – reminiscent of the erection of a circus tent.
A large part of the northern corona was swept away. This (temporarily) opened the northern polar coronal hole.
The base-difference imaging clearly shows how large and energetic this eruption was, with a coronal wave and large-scale dimming. A Type II radio burst was recorded, which is unusual for a filament eruption. The post-eruptive arcades emitted X-rays: a C-class flare (C6) was registered. In coronographs, a large, spherically expanding shock wave could be seen surrounding the CME. Energetic particles were also released, which were measured shortly after the eruption in geostationary Earth orbit.
SOHO LASCO C3
The shock of the CME with about 1000 km/s reached us on 3 April around 1500 UTC. The interplanetary plasma speed then increased to over 850 km/s. The core of the CME probably did not reach us (at least not yet – 2026-04-04 0530z).
2026-04-02 07:17z-11:17z
The shock front in the side view from the Heliospheric Imager of STEREO A. On the last frame you can see how the structure is thinned and washed out by the high-speed stream it gets into. The lower bump is the slower flying toilet lid.
Filament unwinding on 2026-04-02, 1800z with M3.5 flare and CME
Region 4404 had a small, tightly wound core filament that unwound. Some material escaped and produced a CME that could graze us on 5 April.
The narrow CME to the north-west in SOHO LASCO C3 is not particularly impressive
2026-04-03 04:18z
Region 4409 with complexity and M-class flares
The sunspot group shows quite rapid development towards more complexity with strong magnetic shear in the leading section, leading to the production of many solar flares.
Since 4 April, the region has dominated the flare activity on the visible solar disc.
☞ lmsal.com/solarsoft/latest_events
On 4 April at 01:17 UTC it produced a strong M7.55 flare, but probably not a CME – coronagraph data is only available from CCOR-1 to 03:30z, until then nothing can be seen (as of 2026-04-04 0530z)
Marginal dimming north of the region, a few opening field lines and only a few small post-eruptive arcades indicate that little material was able to leave the corona. Nonetheless, a strong microwave radio burst was recorded across the entire spectrum from 24 GHz to below 2 GHz, certainly causing interference to GPS, ADS-B, satellite communications and radar.
☞ Owens Valley Solar Arrays – ovsa.njit.edu
Updates
Solar Synoptic Map, 2026-04-04
… Updates will follow
More updates always on X or bluesky
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