South Africa hit by solar storm

The South African National Space Agency (Sansa) space weather centre reports that a solar storm hit the Earth that impacted satellite navigation systems in South Africa.

Based on data from the United States National Oceanic and Atmospheric Administration (NOAA), a Severe-class solar storm hit on Wednesday and continues as a Minor-class storm on Thursday.

Sansa said the continuous effects of a coronal mass ejection (CME) associated with filament eruptions on Sunday began arriving on Tuesday, 15 April 2025, at approximately 18:36.

These were soon followed by additional CME impacts, leading to a G4/Severe geomagnetic storm on Wednesday.

Sansa said the geomagnetic storm conditions have declined to a G1/Minor level with a planetary K-index of 5 and Disturbance Storm Time (DST) of -74 nT.

The Kp-index is a global indicator for geomagnetic storm intensity on a logarithmic scale ranging from 0 to 9.

DST is an index of magnetic activity derived from a network of near-equatorial geomagnetic observatories that measures the intensity of the globally symmetrical equatorial electrojet, also called the ring current.

Moderate storms are usually between -50 and -100 nT, while geomagnetic superstorms would be less than -250 nT.

While the solar storm conditions have declined, Sansa said that global navigation satellite systems and high-frequency radio could still be impacted.

This is the latest of several solar storms affecting South Africa as the Sun reaches its most active period for solar flares and coronal mass ejections.

South Africans had a rare glimpse of the Aurora Australis or Southern Lights on 10 May 2024 during the “Mother’s Day Storm”.

Sansa said it recorded the strongest Earth-facing solar flare it had seen in seven years on Thursday, 3 May 2024, measuring X9.05.

It explained that solar flares are measured in five categories: A, B, C, M, and X — with X being the strongest.

Solar Maximum

The sun is currently near “solar maximum” — a period of heightened solar activity in the star’s approximately 11-year cycle. Intense solar storms tend to happen near solar maximum.

Solar physicist Dr Keith Strong recently said that NOAA and NASA recently released a new model for the current cycle — Solar Cycle 25.

“The model shows the most probable peak in August 2024 followed by a long, slow decline with solar minimum coming in late 2030 to 2031. Note the Sun has fooled us before!” Strong stated.

Strong’s comments echo those of South African heliospheric physicist Dr Ruhann Steyn, who explained that a solar maximum can only be defined in hindsight.

While it is possible that the most severe CMEs of the current cycle may be behind us, its strongest storms may also be yet to come.