G5 – Extreme geomagnetic storm following strong CME impact

The first set of several incoming coronal mass ejections (CMEs) impacted Earth at around 16:56 UTC on May 10, 2024, rapidly increasing geomagnetic field levels from unsettled to G4 – Severe by 17:44 and to G5 – Extreme by 23:34 UTC — something we haven’t seen since 2003.

A strong CME was registered in solar wind data beginning at around 16:35 UTC and reached Earth at 16:56 UTC, with a 108 nT deviation measured at the Boulder magnetometer. Following initial shock arrival, total field strength increased to a peak of 55 nT while Bz was sustained southward, by as much as -47 nT, after 16:45 UTC.

Solar wind speeds increased sharply to around 700 km/s following shock arrival, with a peak value of 741 km/s observed at 17:35 UTC. Conditions further enhanced later, with Bt reaching 74 nT, Bz deviating southward to near -50 nT, and solar winds peaking over 800 km/s.

The geomagnetic field rapidly increased from unsettled levels to G4, and eventually G5 – Severe geomagnetic storm levels following the CME arrival.

Aurora sightings were widespread in both hemispheres, reaching as far south as Florida, U.S., and the Mediterranean Sea in Europe.

One of the first amazing images came out of New Zealand and Tasmania, described as ‘absolutely biblical.’

The last time Earth had a G5 – Extreme geomagnetic storm was in October 2003, resulting in power outages in Sweden and damaged transformers in South Africa.

Here’s a selection of some of the sightings across the world:

It’s likely this geomagnetic storm was caused by a Cannibal CME — when fast-moving CMEs overtake slower CMEs in front of them and merge into one. Forecast models suggest three of them merged into one yesterday. If so, we still have at least 3 more CMEs coming our way.

Solar researchers believe cannibal CMEs may be the source of ‘complex ejecta’ CME clouds; those with a larger and more complex structure than typical CMEs. These traits cause complex ejecta CMEs to trigger protracted magnetic storms when they envelop the Earth, according to NOAA.

According to SWPC forecasters, periods of G3 – Strong to G5 -Severe geomagnetic storms are expected on May 11 due to continued CME activity.

Periods of G1 – Minor to G2 – Moderate storming are likely on May 12 due to the anticipated arrival of at least two more halo CMEs associated with activity from Region 3664 on May 9 and 10, in addition to the onset of coronal hole high speed stream (CH HSS) influences.

Unsettled and active conditions are expected on May 12 due to waning CME influences and continued CH HSS influences.

For more information about increased solar activity over the past few days, visit: