A big surprise this morning – checking my magnetometer‘s logs I found that it had recorded the strongest magnetic storm since it was built in December 2011:

The weird thing is that the storm was completely unexpected! It’s like hearing a sunny weather forecast and getting the biggest snowstorm in years instead.

The explanation? Spaceweather.com says:

UNEXPECTED GEOMAGNETIC STORM: A strong G3-class geomagnetic storm erupted during the early hours of Jan. 7th, sparking bright auroras around Earth’s poles. What happened? The interplanetary magnetic field (IMF) near our planet tipped south, opening a crack in Earth’s magnetosphere. Solar wind poured in to fuel the strongest magnetic storm since Sept. 2014. NOAA analysts believe the fluctuation in IMF is related to the arrival of a CME originally expected to miss Earth.