The sun fired an M6.9 solar flare, the second-most powerful class of solar eruption, on Tuesday August 25 at approximately 6 AM Eastern, triggering a coronal mass ejection now tracked on a path toward Earth.
An M-class flare sits just below the most powerful X-class events and is strong enough to cause brief radio blackouts on the sunlit side of the planet. Tuesday's eruption produced an R1 minor radio blackout over the Philippine Sea.
The CME is expected to deliver a glancing blow to Earth's magnetic field by approximately 6 to 7 AM Eastern on Friday August 28, though aurora chasers note the arrival window carries roughly a seven-hour uncertainty in either direction.
A glancing impact means the CME does not hit Earth head-on, which generally limits geomagnetic storm intensity.
The current forecast is for a G1 minor storm at most, enough to produce visible auroras near the northern auroral zone but not the kind of widespread display that lit up skies as far south as Florida during the stronger storms of 2024.
The wildcard that could improve Friday's odds: a separate high-speed solar wind stream flowing from a coronal hole on the sun's southern hemisphere is expected to reach Earth around the same time, late August 26 or August 27.
If the CME arrives while that stream is present, the two could combine to enhance geomagnetic activity. If Friday night is clear where you live in the northern tier of the US, northern Europe or Canada, look north after midnight.