Sun Spits out the strongest flare of '25

Not the strongest X-Class flare of Cycle 25, but the strongest flare of the year 2025.  The strongest X flare of Cycle 25 (so far and probably will stay that way) was in July of last year, '24, and was an X14. Today's flare was an X5.1. The strength of the flare isn't generally the whole picture, although it can be. An X5 strength is approximately 0.5 milliwatt per square meter strength, while an X14 is 1.4 mW/sq.mm The bigger story here is that there have been two other Coronal Mass Ejections (CMEs) in the last 48 hours. 

Spaceweather.com puts it this way:  

SEVERE GEOMAGNETIC STORM WATCH: Strong (G3) to severe (G4) geomagnetic storms are possible on Nov. 12th and 13th in response to three CMEs now approaching Earth. This includes a potent CME from today's X5-flare, which is moving so fast it might overtake and sweep up the CMEs ahead of it. The arrival of such a "Cannibal CME" could spark auroras in more than half of all US states. 

A 'GROUND LEVEL EVENT' IS UNDERWAY: Today's X5-class solar flare from sunspot 4274 hurled a fusillade of energetic protons toward Earth. Some of the particles are so powerful, they are penetrating the atmosphere all the way to the ground. "This is a very significant event," says Professor Clive Dyer of the Surrey Space Centre. "Neutron monitors around the world are detecting it."

This is called a Ground Level Event (GLE). GLEs of this magnitude are rare; they happen only once or twice every solar cycle. "This one is comparable to the GLE of Dec. 13, 2006," says Dyer. That makes it a ~20-year event.

When a Flare erupts, the electromagnetic effects of the radio/light it emits arrive here quickly. The particles that constitute the CME (a Coronal Mass Ejection is Mass, after all) so it can't move as fast as light. The geomagnetic storms they talk about in that first indented paragraph are forecast to be here either on the 12th or through the 13th (which I read as midnight on the 13th, so pretty much the 14th).  In UTC it's the 12th now here in the Eastern time zone. Note the couple of days of uncertainty in when it will have effects. 

The arrival of the radio energy from the X5 was close to sunrise here on the coast, while it was midday over Europe and the western areas of Africa. There were stronger effects on radio propagation, with HF being pretty much wiped out for several hours over Africa and Western Europe - good graphic over on Space.com. The Space Weather Prediction Center issued this forecast at around 12 hours after the flare erupted.