Viewing archive of Tuesday, 28 April 2026

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2026 Apr 28 1235 UTC

SIDC Forecast

Solar flares

M-class flares expected (probability >=50%)

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
28 Apr 2026	140	007
29 Apr 2026	135	031
30 Apr 2026	130	029

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares identified. The largest flare was a C9.0 flare (SIDC Flare 7541) peaking on Apr 28 at 09:23 UTC, which was produced by SIDC Sunspot Group 847 (NOAA Active Region 4420). During the flare, the source region (SIDC Sunspot Group 847) of the flare had beta- gamma-delta configuration of its photospheric magnetic field. A total of 7 numbered sunspot groups were identified on the disk over the past 24 hours. SIDC Sunspot Groups 805 and 847 (NOAA AR 4425 and 4420) are the most complex regions with their beta-gamma-delta magnetic configuration. Solar flaring activity is expected to be low to moderate over the next 24 hours, with few C-class flares, possibly M-class flares and a low chance for X-class flares.

Coronal mass ejections

No Earth-directed coronal mass ejections (CMEs) were detected in the available coronagraph observations during the last 24 hour.

Coronal holes

SIDC Coronal Hole (CH) 149, spanning 8 S - 25 S (negative polarity), has crossed the central meridian, and the high-speed streams from this CH may enhance the solar wind environment near Earth during Apr 29 - May 01.

Solar wind

Solar wind conditions have transitioned to slow solar wind regime. The solar wind speed ranged between 355 km/s and 480 km/s. The North-South component (Bz) ranged between -3 and 4 nT. The interplanetary magnetic field ranged from 2 nT to 5 nT. Slow solar wind conditions are expected to continue over the next 24 hours unless the high speed streams from the SIDC Coronal Hole 149, which crossed the central meridian during Apr 26-28 (negative polarity), arrives at Earth.

Geomagnetism

Geomagnetic conditions were globally and locally quiet (NOAA Kp and K BEL 1 to 2). In the next 24 hours, active to minor storm conditions (K 4 to 5) are possible if the high speed streams from the SIDC Coronal Hole 149, which crossed the central meridian during Apr 26-28 (negative polarity), arrives at Earth.

Proton flux levels

The greater than 10 MeV GOES proton flux was below the threshold level over the past 24 hours and it is expected to remain so for the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-19 and GOES-18 satellites, remained below the threshold level over the past 24 hours and is expected to remain so in the coming 24 hours. The 24h electron fluence is presently at normal level and is expected to be at normal to moderate levels in the next 24 hours.

Today's estimated international sunspot number (ISN): 137, based on 18 stations.

Solar indices for 27 Apr 2026

Wolf number Catania	148
10cm solar flux	142
AK Chambon La Forêt	007
AK Wingst	007
Estimated Ap	007
Estimated international sunspot number	134 - Based on 30 stations

Noticeable events summary

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

All times in UTC

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