Many aspects of the extraordinary solar storm of 19 January 2026 have already been discussed in previous newsitems (see the STCE news archive). In this newsitem, the peculiar solar wind conditions that accompanied the passage of the interplanetary coronal mass ejection (CME) are highlighted. The table underneath is based on the solar wind data obtained by the Advanced Composition Explorer (ACE ; since 1998) and the Deep Space Climate Observatory (DSCOVR ; since 2016). Solar wind data obtained by both spacecraft can be accessed online at NOAA/SWPC, and this all the way back to 1998.
The 1-minute data were checked for all solar wind events where either the Bt was larger than 50 nT, Bz lower than -40 nT, OR the solar wind speed ("v") around 1000 km/s or higher. Bt is the total strength of the Interplanetary Magnetic Field (IMF), Bz is the strength of the southward component of this IMF. Both are expressed in nanotesla (nT). The more negative and the longer Bz is negative, the more the geomagnetic field is affected. Note that the ACE sensors measuring particle data such as the solar wind speed, are affected during periods of strong proton events. Hence, for the Bastille day (15 July 2000) and the Halloween events (29 and 30-31 October 2003), the values were used from research papers by Smith et al. (2001) and Skoug et al. (2004). No other efforts were made to calibrate or further polish these data, so the table gives only a general idea of the strongest solar wind events. Over nearly 30 years, there were only 24 events that satisfied any of these criteria, with 17 from solar cycle 23, just 1 from solar cycle 24, and the remaining 6 from the still ongoing solar cycle 25. For each of the 3 parameters Bt, Bz and v, the Top 11 was selected and fit into the table underneath.
From the table, it can readily be seen that the 19 January 2026 storm was one of the strongest in the 28 years of ACE and DSCOVR measurements. It ranks first in terms of strongest Bt (91 nT), second when it comes to the lowest Bz (-58 nT vs -69 nT), and is only surpassed by the two Halloween storms for the highest solar wind speed (1178 km/s vs 1700 or more km/s). Note that for the latter, a higher speed is possible pending further analysis of the January 2026 solar wind data (data affected by the ongoing proton event - see this STCE newsitem). Amazingly, also the storm of 11-12 November 2025 (just a few months ago!) figures in the Top 11 for each of the 3 parameters. Any CME would be proud to see itself just once in this elite table! Truth be told: there have been in the past of course stronger CMEs but for which there were no in-situ solar wind data available, such as the Carrington event (1859) or the August 1972 event. And some strong CMEs such as the July 2012 event (see this STCE newsitem) were not directed to Earth. Nonetheless, this does not diminish the awesome performance of the 19 January 2026 storm.
