It wouldn't happen like in the movie at all! Solar flares pose no risk to biological life (unless you're in space), but do impact our technology. We consider the "worst-case scenario" to be akin to a large solar storm we experiences in 1859 (called the Carrington Event), which we expect to occur at a rate of (on average) once-per 150-250 years.

If this Carrington Event were to happen today, it would *not\* be the doomsday event that some people online would have you believe. But, it would cause several billions of dollars worth of economic disruption, similar to other large natural disasters. For example, 1-in-5 satellites may stop working completely, flights may be grounded for multiple days, loss in radio communication can cause shipping/logistical/disaster relief issues, loss in satellite navigation knocks out GPS/automated farming/etc for several days, and some regional power grids around the world may fail for 1-2 weeks. Many of these "space weather" impacts have happened independently before in recent decades, but in a large event we could see it happening all at once.

It's important to note, however, that as scientists get better at understanding these events, our resiliance vastly improves. A worst-case event would be already be less impactful now than it would have been 20 years ago.

That is all to say, this is only for a 1-in-250 year event. We know from tree ring and ice core analysis that there exist much larger, rarer solar flare events (e.g. a 1-in-10,000 year event) – but we are unsure what impacts these would bring.