Viewing archive of Saturday, 26 July 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Jul 26 1231 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
26 Jul 2025	146	016
27 Jul 2025	144	008
28 Jul 2025	143	008

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours, with only C-class flares. The strongest flares were two C1.2 flares, peaking respectively at 18:07 UTC on July 25, which was associated with SIDC Sunspot Group 572 (NOAA Active Region 4155, magnetic type beta), and at 00:38 UTC on July 26, which was associated with SIDC Sunspot Group 564 (NOAA Active Region 4149, magnetic type beta). There are currently ten numbered active regions on the solar disk. SIDC Sunspot Groups 564, 565, 570, 572 (NOAA Active Regions 4149, 4150, 4153, 4155) are the most complex Groups with magnetic type beta. SIDC Sunspot Group 576 (magnetic type alpha) has emerged in the southeast quadrant. SIDC Sunspot Group 567 (NOAA Active Region 4152) and SIDC Sunspot Group 574 have decayed into plage regions. SIDC Sunspot Group 566 (NOAA Active Region 4151) has rotated over the west limb. The solar flaring activity is expected to be low 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 (CMEs) were observed in the available coronagraph imagery in the last 24 hours.

Coronal holes

A mid-latitude, negative polarity coronal hole (SIDC Coronal Hole 121) started crossing the central solar meridian during the past 24 hours. An associated high-speed stream may arrive at Earth starting from July 29.

Solar wind

Over the past 24 hours, the solar wind parameters (ACE) were enhanced, reflecting the waning influence of the high-speed stream associated with the negative polarity coronal hole (SIDC Coronal Hole 116). Speed values ranged between 460 km/s and 610 km/s. The interplanetary magnetic field values were between 4 nT and 10 nT. The Bz component varied between -4 nT and 7 nT. The interplanetary magnetic field angle was mostly in the negative sector. Currently, the speed values are around 550 km/s and the interplanetary magnetic field is around 11 nT. Further enhanced solar wind conditions may be possible over the next 24 hours, due to the expected arrival of the ICME associated with the partial halo Coronal Mass Ejection (SIDC CME 530) observed around 08:00 UTC on July 23.

Geomagnetism

Geomagnetic conditions globally and locally were mostly at quiet to unsettled levels (NOAA Kp 1 to 3, K BEL 1 to 3). Active to minor storm conditions may be possible globally and locally (NOAA Kp 4 to 5, K BEL 4 to 5) over the next 24 hours, due to the expected arrival of the ICME associated with the partial halo Coronal Mass Ejection (SIDC CME 530) observed around 08:00 UTC on July 23.

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 mostly above the 1000 pfu threshold in the last 24 hours. The greater than 2 MeV electron flux is expected to remain around the 1000 pfu threshold levels in the next 24 hours. The 24-hour electron fluence is presently at moderate levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 156, based on 11 stations.

Solar indices for 25 Jul 2025

Wolf number Catania	211
10cm solar flux	148
AK Chambon La Forêt	014
AK Wingst	012
Estimated Ap	011
Estimated international sunspot number	158 - Based on 23 stations

Noticeable events summary

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

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