The impact of a full halo coronal mass ejection (CME) at Earth on January 19, 2026, drove geomagnetic activity to G4 – Severe levels, producing widespread aurora across Europe, Asia, and the United States.
Geomagnetic storming reached G4 – Severe levels late on January 19 and again early on January 20, 2026, following the arrival of a CME associated with the January 18 X1.9 solar flare.
The CME impact was detected at 19:20 UTC on January 19. Geomagnetic storming evolved rapidly, reaching G2 – Moderate by 19:24 UTC and G3 – Strong by 19:30, before intensifying further to G4 – Severe at 19:43 UTC.
A solar wind signature of a second hit, associated with the CME flux rope arrival on Earth, was observed around 21:00 UTC, with total interplanetary magnetic field reaching 91 nT at 21:15 UTC.
Associated with this second hit, the solar wind speeds measured by the operational satellite reached 1 131 km/s at 21:25 UTC.
Severe storming persisted into the 21:00–24:00 UTC synoptic period, after which geomagnetic activity temporarily eased. During the 00:00–03:00 UTC period on January 20, conditions fluctuated between G1 – Minor and G2 – Moderate, before strengthening again to G2 – Moderate during 03:00–06:00 UTC.
A renewed intensification followed, with geomagnetic activity returning to G4 – Severe levels during the 06:00–09:00 UTC synoptic period. By the 09:00–12:00 UTC period, activity briefly eased to G3 – Strong before intensifying again to severe levels.
At G4 – Severe geomagnetic storm intensity, impacts are primarily expected poleward of 45 degrees geomagnetic latitude. Potential effects include widespread voltage control problems in power systems, with some protective systems potentially tripping to safeguard key assets, and intensified geomagnetically induced currents in pipelines.
Under G4 conditions, satellite systems may experience surface charging, increased drag on low Earth orbit spacecraft, and tracking and orientation problems. Satellite navigation systems, including GPS, may be degraded or inoperable for hours, while high-frequency radio propagation can become sporadic or blacked out at high latitudes.
Auroral activity can expand well into mid-latitudes under these conditions, with visibility possible as far south as Alabama and northern California during peak storming.
“Yesterday’s CME impact was perfectly timed for Europe,” Dr. Tony Phillips of SpaceWeather.com noted. “The severe geomagnetic storm began just after nightfall in the EU, while the New Moon provided dark skies for long-exposure photography.”
An ‘unbelievable’ show was observed in France and Germany, but vivid aurora were also seen in Romania, Belgium, Poland, Switzerland, Latvia, Croatia, Norway, Ireland, Denmark, England, the Czech Republic, the Netherlands, Iceland, and the North Sea.
Amazing aurora visuals were observed as far south as China before moving to the United States and descending as far south as Alabama, Georgia, New Mexico, and California.
The geomagnetic storm coincided with a major solar radiation storm that peaked at S4 – Severe on January 19, the strongest since 2003. The cause was the same – an X1.9 solar flare on January 18.
The most intense radiation phase ended late on January 19, and the latest GOES proton flux data show levels substantially lower, remaining around the S1 – Minor threshold range by late morning on January 20, indicating reduced but still elevated particle conditions.
Further fluctuations in geomagnetic activity remain possible as CME-related structures continue to pass Earth. The storms’ continued intensity depends on solar wind conditions and the orientation and persistence of southward magnetic field components.
Featured image: Northern lights in Brittany, France, seen through the lens of Alexandre Croisier on January 19, 2026. Credit: Alexandre Croisier via SpaceWeather