A strong M6.9 solar flare erupted from Active Region 4513 near the center of the visible solar disk at 10:02 UTC on August 25, 2026, causing an R2 – Moderate radio blackout. NOAA’s Space Weather Prediction Center (SWPC) said the associated CME and a second CME linked to a C4.7 flare and filament eruption later that day contained Earth-directed components, prompting a G2 – Moderate Geomagnetic Storm Watch for August 28. A G1 – Minor watch is in effect for August 27 due to an approaching coronal-hole high-speed stream.
Solar activity reached moderate levels in 24 hours to 12:30 UTC on August 26, with Region 4513 (‘beta-gamma-delta’) producing four M-class flares. The sequence included an M1.9 flare at 01:26 UTC, M1.0 at 04:02 UTC, M1.8 at 06:40 UTC, and the M6.9/1b event at 10:02 UTC.
The M6.9 flare was accompanied by a Type II radio sweep with an estimated velocity of 603 km/s (375 miles/s), a 10.7-cm radio burst of 160 sfu, and a coronal mass ejection first observed by the LASCO/C2 coronagraph at about 11:00 UTC. SWPC subsequently determined that the CME contained an Earth-directed component.
A C4.7/Sf flare at 12:58 UTC was associated with a filament eruption visible in coronagraph imagery after 13:45 UTC. SWPC reported that the CMEs associated with the M6.9 and C4.7 events both contained Earth-directed components and were anticipated to affect geospace on August 28.
A G1 – Minor Geomagnetic Storm Watch is in effect for August 27 for the expected onset of a positive polarity coronal hole high speed stream, and a G2 – Moderate watch for August 28 for the anticipated arrival of the August 25 CMEs.
SWPC expects the coronal hole high speed stream to begin affecting Earth around midday August 27, with solar-wind speeds increasing to about 600 km/s, followed by additional disturbances associated with the approaching CMEs on August 28.
The center forecasts a 55% probability of R1–R2 radio blackouts and a 15% probability of R3 or greater activity on each day from August 26 through August 28, based on the flare potential of Region 4513.
The greater-than-10 MeV proton flux remained below the S1 – Minor solar radiation storm threshold over the past 24 hours. SWPC gives a 10% probability of an S1 or greater solar radiation storm on each day through August 28, while continued activity from Region 4513 remains under observation.
References:
1 Forecast Discussion – NOAA/SWPC – August 26, 2026