CH HSS sparks G2 – Moderate geomagnetic storm
Elevated geomagnetic activity was recorded on Earth on June 13, 2025, due to the waning effects of a negative polarity coronal hole high-speed stream and possible transient effects.
Image credit: NASA SDO/AIA, The Watchers
Waning effects of a negative polarity coronal hole high-speed stream (CH HSS), coupled with possible transient effects, have caused elevated geomagnetic activity on our planet on June 13.
A G1 – Minor geomagnetic storm threshold at 20:34 UTC on June 12, followed by G2 – Moderate at 00:29 UTC on June 13.
The primary area of impact under G2 – Moderate geomagnetic storms is primarily poleward of 55 degrees geomagnetic latitude. Power grid fluctuations may occur, with high-latitude power systems potentially experiencing voltage alarms. Satellite operators may observe orientation irregularities or increased drag on low Earth orbit satellites.
High-frequency (HF) radio propagation could experience fading at higher latitudes, while auroras may become visible as far south as New York, Wisconsin, and Washington state.
A return to nominal conditions is expected late on June 13. By June 14, positive polarity CH HSS influences are expected to begin, with a chance for a weak, glancing blow coronal mass ejection (CME) that left the Sun on June 8. Elevated conditions are likely to linger into June 15, according to the Space Weather Prediction Center (SWPC).
G2 – Moderate geomagnetic storming is likely on June 14, with a slight chance for G3 – Strong levels, due to positive polarity CH HSS influence mixed with possible transient effects from the June 8 CME. By June 15, conditions are anticipated to diminish as CH/CME effects weaken.
Solar activity was at low levels over the past 24 hours, with C-class flares and no Earth-directed CMEs. There is a chance for isolated M-class flares through June 15, primarily due to flare potential from Regions 4105, 4107, and 4115.
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
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