Viewing archive of Saturday, 21 March 2026

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2026 Mar 21 1234 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

Major (ISES: Severe) magstorm expected (A>=100 or K>=7)

Solar protons

Quiet

	10cm flux	Ap
21 Mar 2026	100	085
22 Mar 2026	099	045
23 Mar 2026	098	024

Solar Active Regions and flaring

Solar flaring activity was very low over the past 24 hours. The X-ray flux was below C level. There are currently 3 numbered regions on the disk. SIDC Sunspot Group 820 (NOAA Active Region 4392 magnetic type beta) is the largest region on disk but has been stable over the period. A new region emerged in the southwest quadrant and was numbered SIDC Sunspot group 826 but is simple and quiet. Solar flaring activity is expected to be low over the next 24 hours, with C-class flares probable.

Coronal mass ejections

A halo CME was observed in LASCO C2 coronagraph imagery beginning from 12:24 UTC on March 20. This is determined to be a back-sided event and will not impact the Earth. No new Earth directed CMEs were detected in the available coronagraph imagery.

Coronal holes

An extended negative polarity equatorial coronal hole (SIDC Coronal Hole 147) continues to transit the central meridian.

Solar wind

Over the first half of the period, the solar wind parameters reflected the mild influence of an ongoing ICME passage (SIDC CME 639 of March 16). At 20:17 UTC on March 20, a fast forward shock was detected in the solar wind data (DSCOVR), from another CME arrival (SIDC CME 641 of March 18). The interplanetary magnetic field jumped from about 21 nT to 28 nT, briefly reaching values up to 37 nT. The solar wind speed jumped from approximately 480 km/s to 506 km/s. There were multiple long periods negative Bz values between 19:50 UTC on March 20 to 08:35 UTC on March 21. Bz reached a minimum value of -28 nT at 21:04 UTC on March 20. At the end of the period the interplanetary magnetic field strength was stable around 27 nT with a solar speed of around 500 km/s. The solar wind parameters are expected to remain enhanced over the next 24 hours due to the ongoing ICME passage, and the expected high speed stream associated with the large negative polarity equatorial coronal hole (SIDC Coronal Hole 147).

Geomagnetism

The geomagnetic conditions were at unsettled levels at the start of the period but increased to moderate and then major storm conditions (NOAA KP 7) from 21:00 UTC on March 20, in response to the ICME arrival. Locally, minor storm levels were observed (K-Bel = 5). Minor to moderate storm conditions are expected over the next 24 hours, due to the ongoing ICME influence as well as a high speed stream arrival, with a slight chance for further major storm conditions due to these combined effects.

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, as measured by GOES-18 and GOES-19 satellites, briefly exceeded the 1000 pfu threshold and reached a maximum of 1690 pfu (GOES-18). The greater than 2 MeV electron flux is expected to remain below the 1000 pfu threshold over the next 24 hours. The electron fluence was at normal to moderate levels and is expected to be at normal levels for the next 24 hours.

Today's estimated international sunspot number (ISN): 043, based on 15 stations.

Solar indices for 20 Mar 2026

Wolf number Catania	050
10cm solar flux	102
AK Chambon La Forêt	059
AK Wingst	029
Estimated Ap	032
Estimated international sunspot number	032 - Based on 27 stations

Noticeable events summary

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

All times in UTC

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