Viewing archive of Wednesday, 24 September 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Sep 24 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Quiet

	10cm flux	Ap
24 Sep 2025	169	009
25 Sep 2025	168	008
26 Sep 2025	168	006

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with one M-class flare. The strongest flare was a M1.0 flare (SIDC Flare 5553) peaking at 09:31 UTC on September 24, which was associated with SIDC Sunspot Group 640 (NOAA Active Region 4217, magnetic type beta-gamma). There are currently ten numbered active regions on the solar disk. SIDC Sunspot Groups 592, 640, 650 (NOAA Active Regions 4226, 4217, 4229) are the most complex Groups with magnetic type beta-gamma. SIDC Sunspot Group 621 (NOAA Active Region 4216) has rotated over the west limb. SIDC Sunspot Group 643 (NOAA Active Region 4223) and SIDC Sunspot Group 649 decayed into plage regions. The solar flaring activity is expected to be moderate over the next 24 hours, with C-class flares expected and M-class flares likely.

Coronal mass ejections

No Earth-directed Coronal Mass Ejections (CMEs) were observed in the available coronagraph imagery in the last 24 hours.

Solar wind

Over the past 24 hours, the solar wind parameters (ACE) continued to reflect the ongoing influence of the high-speed stream associated with the mid-latitude negative polarity coronal hole (SIDC Coronal Hole 126). Speed values ranged between 500 km/s and 630 km/s. The interplanetary magnetic field values varied between 5 nT and 7 nT. The Bz component varied between -6 nT and 7 nT. The interplanetary magnetic field angle was mostly in the negative sector. Enhanced solar wind conditions are expected over the next 24 hours under the waning influence of the high- speed stream associated with SIDC Coronal Hole 126.

Geomagnetism

Geomagnetic conditions globally were mostly at quite to unsettled levels (NOAA Kp 2 to 3), with an interval of active conditions (NOAA Kp 4- ) between 12:00 UTC and 15:00 UTC on September 23. Geomagnetic conditions locally were mostly at quite to unsettled levels (K BEL 1 to 3). Mostly quiet to unsettled conditions are expected globally and locally over the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu 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 and GOES 19 was below the 1000 pfu threshold in the last 24 hours. The greater than 2 MeV electron flux is expected to be below the 1000 pfu 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): 156, based on 12 stations.

Solar indices for 23 Sep 2025

Wolf number Catania	210
10cm solar flux	171
AK Chambon La Forêt	019
AK Wingst	017
Estimated Ap	043
Estimated international sunspot number	194 - Based on 16 stations

Noticeable events summary

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

All times in UTC

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