Daily bulletin on solar and geomagnetic activity from the SIDC

Emesso: 2026 May 21 1232 UTC

SIDC Forecast

Brillamenti solari

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

Geomagnetism

Quiet (A<20 and K<4)

Protoni solari

Quiet

	10cm flux	Ap
21 May 2026	114	006
22 May 2026	110	005
23 May 2026	108	004

Solar Active Regions and flaring

Solar flaring activity was very low over the past 24 hours. The X-ray flux was below C level. SIDC Sunspot Group 825 (NOAA Active Region 4436, Beta magnetic configuration) is currently rotating behind the west limb, however a large part of its flaring activity will continue to be detectable in the next 24 hours. Isolated C-class activity is likely during the next 24 hours.

Espulsioni di massa coronale

No Earth-directed Coronal Mass Ejections (CME) were observed in the last 24 hours.

Vento solare

The Solar Wind (SW) conditions of the past 24 hours feature a slow SW regime. The SW speed ranged from 410 to 510 km/s, the interplanetary magnetic field (B) was up to 5 nT, and its North-South component (Bz) varied from -5 to 5 nT. The SW conditions are expected to remain at the current levels in the next 24 hours.

Geomagnetism

The geomagnetic conditions of the past 24 hours reached unsettled levels both globally and locally (NOAA Kp 3 and K BEL 3) on 21 May from 00:00 to 03:00 UTC. The remaining time both global and local conditions were at quiet levels (NOAA Kp 1- to 2+ and K BEL 1 to 2). In the next 24 hours it is likely that they will continue at quiet levels.

Proton flux levels

The greater than 10 MeV proton flux, as measured by the GOES-19 satellite, was at nominal levels over the past 24 hours and is likely to remain so in the next 24 hours.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux as, measured by GOES 19, was around the 1000 pfu alert threshold for past 24 hours. It reached a peak value of 1700 pfu on 20 May at 16:20 UTC. It is expected to marginally drop in the next 24 hours and possibly stay below the alert threshold. The electron fluence was at moderate levels in the past 24 hours and it is likely to drop to normal levels at some point in the next 24 hours.

Today's estimated international sunspot number (ISN): 088, based on 13 stations.

Solar indices for 20 May 2026

Wolf number Catania	086
10cm solar flux	114
AK Chambon La Forêt	013
AK Wingst	010
Estimated Ap	009
Estimated international sunspot number	072 - Based on 24 stations

Noticeable events summary

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