Viewing archive of Sunday, 19 October 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Oct 19 1235 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Minor storm expected (A>=30 or K=5)

Solar protons

Quiet

	10cm flux	Ap
19 Oct 2025	152	035
20 Oct 2025	149	029
21 Oct 2025	149	015

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours with 1 M-class flare recorded. The largest flare was an M1.0 flare (SIDC Flare 5834), peaking on October 19 at 01:56 UTC and was produced by SIDC Sunspot Group 639 (NOAA Active Region 4246). This region is now beyond the west solar limb. There are 6 numbered sunspot groups on disk. SIDC Sunspot group 621 (NOAA Active region 4248), now the most complex region on disk, is also approaching the west solar limb. The remaining regions on disk were mostly quiet. The solar flaring activity is expected to be low over the next 24 hours, with C-class flares expected and a chance for M-class flares.

Coronal mass ejections

No new Earth directed Coronal Mass Ejections (CMEs) were observed.

Solar wind

The solar wind conditions reflected ongoing transient magnetic features, likely associated with the CMEs from October 15 and the start of the high-speed stream influence. The magnetic field ranged between 1 and 17 nT. From 13:00 to 21:00 UTC on October 18, there was a prolonged interval of negative Bz with a value of around -7nT. After this time, the Bz component reduced in magnitude and after 03:00 UTC October 19 became mostly positive. The solar wind speed was between 450 and 550 km/s for most of the period. The solar wind speed is expected to continue to be enhanced over the next 24 hours due to the influence of the high-speed stream associated with the negative polarity coronal hole (SIDC Coronal Hole 126).

Geomagnetism

Geomagnetic conditions reached moderate storm levels globally (Kp 6), between 18:00 and 21:00 UTC on October 18, likely due to the ongoing influence of a glancing blow arrival of the CME of October 15. Locally, minor storm conditions were reached (K Bel 5). Active to minor storm conditions (Kp 4-5) are expected over the next 24 hours in response to the high-speed stream influence.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu threshold over the past 24 hours. It is expected to remain below this threshold level over the next 24 hours. There is a small chance of an increase related to any high-level flaring, particularly from SIDC Sunspot Group 639 (NOAA Active Region 4246) while it remains near the west solar limb.

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): 107, based on 05 stations.

Solar indices for 18 Oct 2025

Wolf number Catania	///
10cm solar flux	156
AK Chambon La Forêt	059
AK Wingst	037
Estimated Ap	040
Estimated international sunspot number	111 - Based on 18 stations

Noticeable events summary

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

All times in UTC

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