Planetary K-index produced by SANSA with the disturbance storm time (Dst) as the black line

March 24, 2023

A severe geomagnetic storm caused by a coronal mass ejection (CME) from the Sun arrived late on Thursday 23 March and continues to impact the Earth and its technological systems today.

The CME was ejected from the Sun on Monday 20 March and took approximately three days to arrive on Earth. A CME is a large cloud of high-energy particles ejected from the surface of the Sun when stored energy is suddenly released.  When the magnetic field of a CME interacts with the Earth’s magnetic field it causes a temporary disturbance known as a geomagnetic storm. The CME may impact technological systems such as Global Navigation Satellite Systems and High-Frequency radio communications.

Dr Mpho Tshisaphungo, SANSA’s Head of Space Weather says the SANSA Space Weather Centre originally forecasted that the anticipated CMEs would give Earth a glancing blow and cause a G1/minor to G2/moderate geomagnetic storm. However, the storm reached G4 or severe conditions on Friday morning. The planetary K-Index, which indicates how disturbed the Earth’s magnetic field is, was at Kp 7 on Thursday morning 23 March, indicating a strong storm. The local Hermanus K-index reached the value of 6, moderate storm level. Dr Tshisaphungo says every space weather storm is unique and needs to be analysed thoroughly and monitored closely to evaluate regional impacts on Earth.

The current severe storm is the first of this current solar cycle with a Kp 8 magnitude. According to Dr Martin Snow, SANSA SARChI Research Chair in Space Weather, a G4 storm is characterized as “severe,” and is uncommon.  “Historically, storms of this magnitude only happen a few times per year during the peak of the solar cycle.  HF radio communication can be interrupted for hours at a time, spacecraft can experience electrical problems, and the power grid is prone to additional voltage fluctuations.”

SANSA’s operational Space Weather Centre was launched by Dr Blade Nzimande, Minister of Higher Education, Science and Technology on 2 November 2022. This centre monitors the Sun and near-Earth environment on a 24/7 basis to forecast geomagnetic storms that could impact technological systems.

Please report any anomalies you may have experienced while operating drones or using GPS navigation during this period to SANSA at