Overview
- An X1.9-class flare on Jan. 18 launched a full-halo CME that struck Earth on Jan. 19, with NOAA logging G4 (severe) geomagnetic storm levels around 19:38 GMT.
- GOES measurements showed ≥10 MeV proton flux exceeding 1,000 pfu on Jan. 19, prompting an S3 solar radiation storm alert that NOAA described as among the strongest since 2003.
- Bright auroras were reported across the UK, much of Canada, northern and central U.S. states, and parts of Europe, with sightings reaching as far south as Alabama, northern California, and northern Italy.
- NOAA and national forecasters warned of possible effects on power grids, satellites, HF radio and GNSS, and elevated radiation exposure on high-latitude flights, with no widespread infrastructure failures confirmed.
- Outlooks from NOAA and the UK Met Office indicate geomagnetic activity will diminish, though localized aurora remains possible at higher latitudes as agencies continue real-time monitoring.