Viewing archive of Tuesday, 18 March 2025

Daily bulletin on solar and geomagnetic activity from the SIDC

Issued: 2025 Mar 18 1241 UTC

SIDC Forecast

Solar flares

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

Geomagnetism

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

Solar protons

Quiet

	10cm flux	Ap
18 Mar 2025	210	014
19 Mar 2025	215	010
20 Mar 2025	220	013

Solar Active Regions and flaring

Solar flaring activity was moderate over the past 24 hours, with one M-class flare identified. The largest flare was a M1.0 flare (SIDC Flare 3870) peaking on March 17 at 19:33 UTC, which was associated with a filament eruption near SIDC Sunspot Group 445 (NOAA Active Region 4033). This region had a simple magnetic configuration and has now decayed. SIDC Sunspot Groups 405, 436, 440 (NOAA Active Region 4028, 4025 and 4031) are the largest and most complex regions on disk with Beta-Gamma magnetic configuration. There are currently a total of 13 numbered sunspot groups on disk. Solar flaring activity is expected to be moderate over the next 24 hours, with C-class flares expected and M-class flares likely.

Coronal mass ejections

The faint partial halo CME, previously reported, that was observed to the north-east first seen in SOHO/LASCO-C2 data from 20:12 UTC March 16, has been assessed to be associated with an on-disk eruption and dimming observed in the north-east quadrant from 19:00 UTC in SDO/AIA 193 for which a glancing blow at Earth may be possible from early on March 20. A filament eruption was observed in the north-west quadrant on March 17 around 10:30 UTC. The associated CME as seen in SOHO/LASCO-C2 data from 11:24 UTC is slow and is predominantly directed to the west but is deemed to have a possible Earth-directed component with a glancing blow possible on March 21. A CME was observed associated with the M1.0 flare and filament eruption near SIDC Sunspot Group 445 (NOAA Active Region 4033). This CME seen in SOHO/LASCO-C2 data from 20:00 UTC March 17 is directed to the north and is not expected to be Earth directed.

Solar wind

The solar wind speed ranged between 370 and 430 km/s. The interplanetary magnetic field ranged between 4 and 8 nT with a minimum Bz value of -7 nT. The solar wind speed is expected to be slightly elevated on March 18, due to the influence of the high-speed stream associated with the negative polarity coronal hole which began to cross the central meridian March 13. Slow solar wind conditions are expected on March 19.

Geomagnetism

In the past 24 hours, geomagnetic conditions were quiet to active (Kp = 4). Geomagnetic conditions are expected to be at quiet to unsettled levels with intervals of active periods possible on 18 due to the possible high-speed stream effects.

Proton flux levels

The greater than 10 MeV proton flux as measured by GOES-18 remained below the 10 pfu threshold and is expected to remain so over the next days.

Electron fluxes at geostationary orbit

The greater than 2 MeV electron flux, as measured by GOES-18, exceeded the 1000 pfu threshold between March 17 14:10 UTC and March 18 02:20 UTC and is expected to increase above the threshold again during the next 24 hours. The 24h electron fluence was at moderate levels and is expected to remain so for the next day.

Today's estimated international sunspot number (ISN): 194, based on 18 stations.

Solar indices for 17 Mar 2025

Wolf number Catania	214
10cm solar flux	204
AK Chambon La Forêt	025
AK Wingst	016
Estimated Ap	016
Estimated international sunspot number	202 - Based on 22 stations

Noticeable events summary

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

All times in UTC

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