Viewing archive of Monday, 20 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 20 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
20 Oct 2025	146	012
21 Oct 2025	144	013
22 Oct 2025	144	007

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with two M-class flares recorded. The largest flare was an M1.8 flare (SIDC Flare 5840), peaking on October 19 at 20:15 UTC, originating from behind the west limb and likely associated with SIDC Sunspot Group 639 (NOAA Active Region 4246). SIDC Sunspot Group 621 (NOAA Active Region 4248), which is now rotating over the west limb, produced an M1.0 flare (SIDC Flare 5845), peaking on October 20 at 05:27 UTC. Isolated low-level flaring was also produced by active regions behind the east limb. The remaining active regions on the disk are relatively simple (magnetic type alpha or beta) and did not produce any significant flaring activity. Solar flaring activity is expected to be at low to moderate levels over the next 24 hours, with C-class flares very likely and a 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 were slightly disturbed under the influence of a high-speed stream (HSS). The interplanetary magnetic field reached values up to 10 nT before decreasing to around 4 nT. The solar wind speed ranged between 500 and 650 km/s. The southward component of the interplanetary magnetic field fluctuated between -10 nT and 8 nT. The magnetic field orientation was predominantly in the negative sector (field directed towards the Sun). Solar wind conditions are expected to remain slightly elevated over the next days due to the influence of a high-speed stream from a recurrent negative polarity coronal hole (SIDC Coronal Hole 126).

Geomagnetism

Geomagnetic conditions were quiet to unsettled both globally and locally over Belgium (NOAA Kp: 1 to 3; K-Bel: 1 to 3). Mostly unsettled geomagnetic conditions are expected over the next 24 hours, with a chance of isolated active periods due to the ongoing high-speed stream influence.

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): 109, based on 12 stations.

Solar indices for 19 Oct 2025

Wolf number Catania	///
10cm solar flux	149
AK Chambon La Forêt	022
AK Wingst	020
Estimated Ap	020
Estimated international sunspot number	110 - Based on 09 stations

Noticeable events summary

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

All times in UTC

<< Go to daily overview page