Viewing archive of Thursday, 29 May 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 May 29 1238 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Moderate (ISES: Major) magstorm expected (A>=50 or K=6)

Solar protons

Quiet

	10cm flux	Ap
29 May 2025	148	060
30 May 2025	152	041
31 May 2025	154	026

Solar Active Regions and flaring

Solar flaring activity was low over the past 24 hours. The largest flare was a C7.0 flare (SIDC Flare 4490) peaking on May 29 at 03:01 UTC, which was produced by SIDC Sunspot Group 469 (NOAA Active Region 4100, magnetic type Beta-Gamma). SIDC Sunspot group 508 (NOAA Active region 4099, magnetic type Beta-Delta) produced C-class flaring. There were 9 numbered sunspot groups on the disk over the past 24 hours, the rest of these regions were simple and mostly quiet. The solar flaring activity is expected to be moderate over the next 24 hours, with M-class flares expected and a chance for X-class flares.

Coronal mass ejections

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

Coronal holes

An extended equatorial coronal hole (combined SIDC Coronal Hole 116 and 112) continues to transit the central meridian since May 26.

Solar wind

The solar wind conditions reflected the arrival of the high- speed stream associated with the large equatorial coronal hole that first began to cross the central meridian on May 26. The solar wind speed increased showed a decreasing trend until 23:00 UTC on May 28, after which it began to gradually increase from 380 km/s to a maximum value around 730 km/s at the end of the period. The interplanetary magnetic field also increased around 00:00 UTC with a maximum value of 24 nT and the Bz component reached a minimum value of -24 nT at this time. The interplanetary magnetic then decreased to values around 11 nT for the rest of the period. The interplanetary magnetic field phi angle was mostly in the negative sector. Further enhanced solar wind conditions are expected over the next days due to the ongoing high-speed stream.

Geomagnetism

Geomagnetic conditions reached major storm levels globally (Kp 7-) between 00:00 UTC and 03:00 UTC on May 29. This is due to the arrival of the high-speed stream associated with the negative polarity coronal hole that began crossing the central meridian on May 26 (SIDC Coronal Hole 116 and 112). Locally, only minor active storm conditions were observed (K Bel 4). The conditions then reduced and are at minor storm levels at the end of the period. Minor storm conditions expected to continue over the next 24 hours with isolated intervals of moderate storm conditions possible, due to the ongoing impact of the high-speed stream.

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.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux measured by GOES 18 and GOES 19 were 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 remain so over the next 24 hours.

Today's estimated international sunspot number (ISN): 107, based on 12 stations.

Solar indices for 28 May 2025

Wolf number Catania	139
10cm solar flux	144
AK Chambon La Forêt	034
AK Wingst	///
Estimated Ap	024
Estimated international sunspot number	114 - Based on 23 stations

Noticeable events summary

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

All times in UTC

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