# Geomagnetic activity fluctuations

> Live situation record from CLSTR: https://clstr.news/situations/geomagnetic-activity-fluctuations
> Updated: 2026-09-14T05:00:43.000Z. Sources: 2. Developments: 2.

Following a period of activity around September 8 where the Kp index reached 5, resulting in a G1-class storm, geomagnetic activity was forecasted to remain low for September 12. During this period, the planetary Kp index was expected to reach a maximum of approximately 2.67, well below the threshold for a G1 “weak” geomagnetic storm.

By September 15, forecasts indicated a shift toward moderate activity. Data from the NOAA Space Weather Prediction Center suggested a 30% probability of a brief G1-class minor geomagnetic storm, potentially driven by a high-speed stream from a coronal hole. The predicted Kp index for this period was expected to peak at 3.67.

## Timeline

### 2026-09-14: Space weather forecast predicts potential minor geomagnetic storm for September 15, 2026

Space weather forecasts for September 15, 2026, predict moderate geomagnetic activity with a 30% chance of a minor G1-class storm due to a high-speed solar wind stream from a coronal hole.

2 sources. https://clstr.news/cluster/space-weather-forecast-predicts-potential-minor-geomagnetic-storm-for-september-15-2026

### 2026-09-11: NOAA forecasts low geomagnetic activity for September 12, 2026

No significant geomagnetic storms are expected on September 12, 2026, as the Kp index is projected to remain below 3, according to NOAA and other space weather forecasting services.

2 sources. https://clstr.news/cluster/noaa-forecasts-low-geomagnetic-activity-for-september-12-2026

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Cite as: Geomagnetic activity fluctuations. CLSTR, https://clstr.news/situations/geomagnetic-activity-fluctuations