Viewing archive of Tuesday, 21 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 21 1231 UTC

SIDC Forecast

Solar flares

C-class flares expected, (probability >=50%)

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
21 Oct 2025	136	011
22 Oct 2025	138	007
23 Oct 2025	138	007

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with several C-class flares recorded. The largest flare was a C3.6 flare (SIDC Flare 5850), peaking on October 21 at 06:49 UTC, associated with the ARs behind the east limb. There are currently eleven numbered active regions on the visible solar disk. Two new regions have emerged: SIDC Sunspot Group 679 (NOAA Active Region 4263; magnetic type beta) currently located at N05W02, and SIDC Sunspot Group 678 (NOAA Active Region 4262; magnetic type alpha) near S13E34, but remained quiet. Low flaring activity was also produced by SIDC Sunspot Group 674 (NOAA Active Region 4257; magnetic type beta) and by active regions behind the west limb, likely associated with SIDC Sunspot Group 621 (NOAA Active Region 4248). The remaining active regions are relatively simple (magnetic type alpha or beta) and did not produce any significant flaring activity. Solar flaring activity is expected to be low over the next 24 hours, with C-class flares probable and a small chance for M-class flares.

Coronal mass ejections

No Earth-directed coronal mass ejections (CME) have been detected in the available coronagraph imagery over the past 24 hours.

Solar wind

Over the past 24 hours, the solar wind parameters (ACE and DSCOVR) reflected the waning influence of a high-speed stream (HSS). The solar wind speed decreased from around 570 km/s to 450 km/s. The interplanetary magnetic field remained weak, below 6 nT, and its southward component fluctuated between -5 nT and 6 nT. Solar wind conditions are expected to gradually return to a slow solar wind regime over the next days.

Geomagnetism

Geomagnetic conditions were quiet to unsettled both globally and locally over Belgium (NOAA Kp: 1 to 3; K-Bel: 1 to 3). Mostly quiet geomagnetic conditions are expected over the next 24 hours.

Proton flux levels

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

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 was below the 1000 pfu threshold. The greater than 2 MeV electron flux is expected to remain below the 1000 pfu threshold over the next 24 hours. The 24-hour electron fluence was at normal levels and is expected to be at normal levels over the next 24 hours.

Today's estimated international sunspot number (ISN): 119, based on 07 stations.

Solar indices for 20 Oct 2025

Wolf number Catania	124
10cm solar flux	140
AK Chambon La Forêt	015
AK Wingst	008
Estimated Ap	008
Estimated international sunspot number	111 - Based on 19 stations

Noticeable events summary

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

All times in UTC

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