Apparently, the sun is approaching what's known as solar maximum—the high point in its roughly 11-year cycle of activity, according to National Geographic. Scientists anticipate stronger storms around solar max, in 2013.  Flares have occurred almost daily, and may be monitored online or with iPad applications like Solar Monitor Pro.  Flares can precipitate warnings for multiple types of interest the most significant be S3 through S5 which may represent health risks to all occupants of aircraft at typical flight levels.