Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Apr 02 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
02 Apr 2025	183	031
03 Apr 2025	181	019
04 Apr 2025	179	024

Solar Active Regions and flaring

Solar flaring activity was moderate, with one M-class flare and multiple C-class flares recorded over the past 24 hours. The largest flare was an M2.5 flare (SIDC Flare 4005) peaking at 22:31 UTC on April 01, associated with SIDC Sunspot Group 461 (NOAA Active Region 4048, beta-gamma-delta). There are currently seven numbered active regions visible on the solar disk. SIDC Sunspot Group 461 (NOAA Active Region 4048; beta-gamma-delta), that remains the largest and magnetically most complex active region on the disk, was the main driver of the flaring activity observed over the past 24 hours together with SIDC Sunspot Group 456 (NOAA AR 4044; beta). SIDC Sunspot Group 460 (NOAA AR 4047; beta) is now approaching the west limb. Low flaring activity was also produced by SIDC Sunspot Group 458 (NOAA AR 4045; alpha) and SIDC Sunspot Group 462 (NOAA AR 4049; beta). Solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares very 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) reflected ongoing ICME influence. The total interplanetary magnetic field reached values of up to 15 nT. The solar wind speed ranged between 390 km/s and 470 km/s. The southward component of the interplanetary magnetic field reached a minimum of -9 nT. Solar wind conditions are expected to remain slightly elevated due to the ICME passage over the next day, before gradually returning to slow solar wind conditions. From April 04, the solar wind parameters are expected to become slightly elevated due to the possible arrival of a high-speed stream from a negative polarity coronal hole that began crossing the central meridian on April 01.

Geomagnetism

Geomagnetic conditions over the past 24 hours reached active levels both globally and locally over Belgium (NOAA Kp: 4+; K-Bel: 4). Mostly quiet to unsettled conditions are expected over the next few days, with a chance of isolated active or minor storm periods on April 2 due to ongoing ICME influence. From April 4, active conditions are expected, with a possible isolated minor storm interval in response to the arrival of the high-speed stream.

Proton flux levels

The greater than 10 MeV proton flux has been gradually decreasing over the past 24 hours and has remained below the 10 pfu threshold since 09:25 UTC on April 2. The proton flux is expected to gradually return to nominal levels over the next few days, with a chance of exceeding minor storm levels if any high-energy flares or eruptions occur.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-18, exceeded the 1000 pfu threshold between 12:45 UTC on April 01 and 01:10 UTC on April 02, 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 at moderate levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 136, based on 17 stations.

Solar indices for 01 Apr 2025

Wolf number Catania	///
10cm solar flux	182
AK Chambon La Forêt	020
AK Wingst	007
Estimated Ap	007
Estimated international sunspot number	155 - Based on 26 stations

Noticeable events summary

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