We have another geomagnetic storm coming our way. The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) has issued a warning about a G3 [strong] geomagnetic storm for December 9 due to a recent coronal mass ejection (CME) event. The event occurred on December 7 from the Sun’s Region 4299 which is currently facing Earth.
A full-halo coronal mass ejection (CME), associated with an M8.1 flare from Region 4299 at 20:39 UTC on 06 December, is expected to impact Earth early to midday on 09 December, potentially causing periods of G3 (Strong) geomagnetic storming. pic.twitter.com/L2qCfEWmRW
— NOAA Space Weather Prediction Center (@NWSSWPC) December 7, 2025
What are coronal mass ejections?
Coronal mass ejections are the release of huge clouds of electrically charged particles called plasma from the Sun’s corona – the outer atmospheric layer. These clouds weigh billions of tons and the particles can travel millions of kilometres into outer space.
When directed toward Earth, the plasma travelling fast after a violent eruption can reach us within a few hours; the slower ones take a couple of days or more. When the charged particles interact with Earth’s magnetosphere and atmosphere, they cause a disturbance which results in a geomagnetic storm.
Earth witnesses CME and solar flare
Apart from the CME, the weather prediction center also flagged a solar flare event from Region 4298 today. Solar flares are intense bursts of light and they are the most powerful explosions in the solar system. According to NASA, the biggest flares can have energy equivalent to a billion hydrogen bombs. The flares and CMEs are closely related but they don’t always occur simultaneously.
Sunspot Region 4299 ☀️ Two solar flares 1) M1.1 triggered 2) M8.1 – both produced a coronal mass ejection 1) slower, to NE 2) faster, earth-directed – possible arrival 8/9 December
Base difference imagery SDO AIA 171/193/211 is showing dimming regions pic.twitter.com/6hVgIhxq5Q
— Marko Rummelsburg (@doktornihil) December 7, 2025
The strength of flares are divided into five classes – A, B, C, M and X – with A being the weakest and X being the strongest. December 8’s flare was classified as X1.1/2b.
Meanwhile, the CME event is predicted to impact Earth tomorrow. According to the SWPC, the subsequent geomagnetic storm may have minor effects on technological infrastructure and auroras may be visible over the polar regions and the US.
A solar storm is launching now in the Earth-strike zone! Region 4299 is once again waking up, albeit with only minor M-class flaring, but along with its nearby unstable filaments, this is enough to cause a large eruption. Waiting for the eruption to finish and for coronagraph… pic.twitter.com/OoUUj1hHfF
— Dr. Tamitha Skov (@TamithaSkov) December 6, 2025
Space weather physicist Dr. Tamitha Skov shared a footage of the recent solar eruption from Region 4299. “A solar storm is launching now in the Earth-strike zone! Region 4299 is once again waking up, albeit with only minor M-class flaring, but along with its nearby unstable filaments, this is enough to cause a large eruption,” she posted on December 7.
In another post today, Skov revealed that the solar flare from Region 4298 caused radio blackout on Earth’s dayside. “Expect HF/VHF radio band degradation, especially near Asian Pacific, Eastern Russia, China, India, & East Africa. A third solar storm launching too!” she wrote.
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