http://www.newsweek.com/sunspot-magnetic-field-x-class-solar-flare-1772206

The sun has woken up grumpy this week, developing unusually unstable magnetic fields at some sunspots that may result in rare and violent X-class solar flares being fired at the Earth.

X-class flares are the most powerful type of solar flare, and can lead to planet-wide radio blackouts and radiation storms if they hit the Earth.