Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Apr 20 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
20 Apr 2025	159	011
21 Apr 2025	161	017
22 Apr 2025	163	016

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been low, with few C-class flares. The strongest flare was a C4.3 flare (SIDC Flare 4158) peaking at 16:28 UTC on April 19, associated with SIDC Sunspot Group 476 (NOAA Active Region 4065, magnetic type beta). There are currently seven numbered active regions on the solar disk. The most complex one is SIDC Sunspot Group 473 (NOAA Active Region 4062, magnetic type beta-gamma). A new, currently unnumbered active region (SIDC Sunspot Group 479, magnetic type beta) has emerged in the southwest quadrant. A new, currently unnumbered active region (SIDC Sunspot Group 480) is rotating on disc from the southeast limb. The solar flaring activity is expected to be low to moderate over the next 24 hours, with C-class flares expected and M-class flares probable.

Coronal mass ejections

A filament eruption was observed in SDO/AIA 304 data around 15:20 UTC on April 19 in the northeast quadrant, north of SIDC Sunspot Group 473 (NOAA Active Region 4062). No associated Coronal Mass Ejection (CME) was observed in the available coronagraph imagery. No other Earth-directed CMEs were observed in the available coronagraph imagery.

Coronal holes

The southern, mid-latitude, positive polarity coronal hole (SIDC Coronal Hole 104) continues to cross the central meridian since April 17.

Solar wind

The solar wind conditions (ACE and DSCOVR) were enhanced during the past 24 hours, likely due to the arrival of a high-speed stream from the southern, positive polarity coronal hole (SIDC Coronal Hole 104). The solar wind speed reached 450 km/s. The interplanetary magnetic field increased from 6 nT to 10 nT. The Bz component initially was mostly negative, between -5 nT and -7 nT, before flipping to positive around 23:00 UTC on April 19, with values between 3 nT and 5 nT. The interplanetary magnetic field angle was in the negative sector until 23:00 UTC on April 19, when it flipped to the positive sector. Further enhancements in the solar wind conditions may be expected over the next 24-48 hours, under the continuous influence of the high-speed stream from the southern, positive polarity coronal hole (SIDC Coronal Hole 104) and the possible arrival of the high-speed stream from the equatorial, positive polarity coronal hole (returning SIDC Coronal Hole 82).

Geomagnetism

Geomagnetic conditions globally and locally reached minor storm levels (NOAA Kp 5) between 00:00 UTC and 03:00 UTC on April 20. Mostly unsettled to active levels, with possible minor storm intervals (NOAA Kp 3 to 5, K BEL 3 to 5), are expected globally and locally over the next 24-48 hours, under the continuous influence of the high-speed stream from the southern, positive polarity coronal hole (SIDC Coronal Hole 104) and the possible arrival of the high-speed stream from the equatorial, positive polarity coronal hole (returning SIDC Coronal Hole 82).

Proton flux levels

The greater than 10 MeV proton flux was below the threshold level over the past 24 hours. It is expected to remain below the threshold level over the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 was over the threshold between 20:15 UTC and 21:25 UTC on April 19. The greater than 2 MeV electron flux measured by GOES 19 was below the threshold over the past 24 hours. The greater than 2 MeV electron flux is expected to remain below the threshold over the next 24 hours. The 24-hour electron fluence is presently at normal levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 125, based on 15 stations.

Solar indices for 19 Apr 2025

Wolf number Catania	///
10cm solar flux	157
AK Chambon La Forêt	032
AK Wingst	022
Estimated Ap	023
Estimated international sunspot number	111 - Based on 15 stations

Noticeable events summary

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