Viewing archive of Monday, 26 May 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 May 26 1232 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Quiet (A<20 and K<4)

Solar protons

Warning condition (activity levels expected to increase, but no numeric forecast given)

	10cm flux	Ap
26 May 2025	138	006
27 May 2025	142	006
28 May 2025	144	015

Solar Active Regions and flaring

Solar flaring activity over the last 24 hours has been moderate, with one M-class flare. The strongest flare was an M8.9 flare (SIDC Flare 4460) peaking on May 25 at 16:30 UTC, which was produced by SIDC Sunspot Group 506 (NOAA Active Region 4098, magnetic type beta-gamma-delta). This is the most complex region on disk and produced most of the flaring activity. SIDC Sunspot Group 508 (NOAA 4099) also produced low level C-class flares. The seven other numbered active regions on the solar disk were quiet. SIDC Sunspot Group 469 (NOAA AR 4100, magnetic type beta), a returning region, has rotated onto the disk over the east limb. The solar flaring activity is expected to be low over the next 24 hours, with C-class flares expected and further M-class flares possible.

Coronal mass ejections

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

Coronal holes

The small equatorial, negative polarity coronal hole (returning SIDC Coronal Hole 99) that crossed the central meridian on May 25 is now on the western hemisphere. An extended mid-latitude to equatorial coronal hole (SIDC Coronal Hole 116), also with negative polarity, began to transit the central meridian on May 26. An associated high-speed stream is expected to arrive at Earth from May 29.

Solar wind

The solar wind conditions reflected a slow solar wind regime. The solar wind speed ranged between 330 km/s to 495 km/s. The interplanetary magnetic field ranged between 2 nT and 11 nT. The Bz component ranged between -9 nT and 9 nT. The interplanetary magnetic field angle phi was mostly in the positive sector. Slow solar wind conditions are expected over the next 24 hours.

Geomagnetism

Geomagnetic conditions globally and locally were at quiet levels (NOAA Kp 2, K BEL 2) over the past 24 hours. Quiet conditions are expected over the next 24 hours.

Proton flux levels

The greater than 10 MeV proton flux was below the 10 pfu threshold over the past 24 hours. It is expected generally to remain below this threshold level over the next 24 hours, but a chance of an increase remains due to any high-level flaring activity from SIDC Sunspot Group 506 (NOAA Active Region 4098) as it approaches the west limb.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 crossed the 1000 pfu threshold between 17:35 and 23:05 UTC on May 25. The greater than 2 MeV electron flux measured by GOES 19 was just 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 is presently at normal levels and is expected to remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 124, based on 20 stations.

Solar indices for 25 May 2025

Wolf number Catania	///
10cm solar flux	133
AK Chambon La Forêt	010
AK Wingst	///
Estimated Ap	009
Estimated international sunspot number	103 - Based on 21 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