Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Mar 31 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Active conditions expected (A>=20 or K=4)

Solar protons

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

	10cm flux	Ap
31 Mar 2025	173	022
01 Apr 2025	175	031
02 Apr 2025	175	024

Solar Active Regions and flaring

Solar flaring activity reached high levels, with six M-class flares and multiple C-class flares recorded over the past 24 hours. The largest flare was an M1.6 flare (SIDC Flare 3960) peaking at 16:42 UTC on March 30, associated with SIDC Sunspot Group 461 (NOAA Active Region 4048; beta-gamma). There are currently seven numbered active regions visible on the solar disk. A new active region, SIDC Sunspot Group 462 (NOAA Active Region 4049), has emerged in the northeastern quadrant. SIDC Sunspot Group 461 (NOAA Active Region 4048; beta-gamma), which is the largest and one of the magnetically most complex active regions on the disk, was the main driver of the flaring activity observed over the past 24 hours. Low flaring activity was also produced by SIDC Sunspot Group 459 (NOAA Active Region 4046; beta-gamma). Solar flaring activity is expected to be moderate to high over the next 24 hours, with M-class flares likely and a small chance for X-class flares.

Coronal mass ejections

No Earth-directed Coronal Mass Ejections (CMEs) have been detected in the available coronagraph images.

Solar wind

Over the past 24 hours, the solar wind parameters (ACE and DSCOVR) have reflected a return to slow solar wind conditions. The interplanetary magnetic field was below 8 nT. The solar wind speed decreased from values about 450 km/s to 400 km/s. The magnetic field orientation was predominantly in the positive sector (directed away from the Sun). A shock was observed in the solar wind data around 10:16 UTC on March 31. The interplanetary magnetic field jumped from 8 nT to 11 nT, and the solar wind speed increased from 420 km/s to 445 km/s. This shock is related to an ICME arrival, likely associated with a partial-halo coronal mass ejection observed on March 28. Solar wind conditions are expected to remain slightly elevated due to the ICME passage and a possible arrival of a high-speed stream from a positive polarity coronal hole

Geomagnetism

Geomagnetic conditions over the past 24 hours were quiet globally (NOAA Kp: 1-2) and quiet to unsettled locally over Belgium (K-Bel:1-3). Active to minor storm conditions may be possible over the next 24 hours, due ICME arrival associated with a partial halo CME that was observed lifting from the Sun on Mar 28, and possible HSS arrival.

Proton flux levels

Over the past 24 hours the greater than 10 MeV GOES proton flux exceeded the 10pfu threshold, reaching a maximum value of 10.5 pfu as measured by GOES-18 at 11:05 UTC on March 31. This is probably related to the partial halo coronal mass ejection observed on March 28. The greater than 10 MeV proton flux is expected to remain elevated with a chance of exceeding the minor storm levels in the coming days.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-18, exceeded the 1000 pfu threshold between 12:40 UTC on March 30 and 03:45 UTC on March 30, but is expected to remain below that threshold over the next 24 hours. The 24-hour electron fluence was at moderate levels and is expected to remain so for the next 24 hours.

Today's estimated international sunspot number (ISN): 143, based on 19 stations.

Solar indices for 30 Mar 2025

Wolf number Catania	///
10cm solar flux	171
AK Chambon La Forêt	009
AK Wingst	005
Estimated Ap	005
Estimated international sunspot number	121 - Based on 25 stations

Noticeable events summary

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