From the London Mail [caution, tabloid]:
Earth is set to be hit by a powerful surge of charged particles from the sun beginning on Wednesday. Officials issued an alert today around 12pm ET, warning that the incoming solar activity could trigger a severe geomagnetic storm, reaching the G4 level on NOAA’s scale.
G4 is the second-highest classification, capable of causing widespread technological impacts, and the alert noted the possibility that levels could be even higher. The US Space Weather Prediction Center (SWPC) said some electrical grid systems may temporarily shut down, spacecraft could experience increased drag or surface charging, and high-frequency radio signals may be spotty or blackout for hours.