From 24 to 30 August the Sun stayed relatively calm, with low geomagnetic activity. The exception came on 30 Aug 2025 (20:02 UTC), when active region AR 4199 produced a long-duration M2.7 flare and a halo CME directed toward Earth. Official models point to possible disturbances in early September.
Extended technical summary
Flares >M: M2.7 (peak 20:02 UTC, 30 Aug) from AR 4199; a few smaller M-class events appeared mid-week (GOES XRS).
CMEs: The 30 Aug eruption launched a broad/halo CME seen in SOHO/LASCO C2/C3, with speeds near ~1,260–1,300 km/s and half-widths ~34°–53°; DONKI links it to the M2.7 (onset ~19:11–20:09 UTC).
Solar wind at L1 (DSCOVR): Background week without clear shocks; V ~350–420 km/s, Bz excursions of only a few nT (down to ~−6 nT), density ~3–10 cm⁻³—consistent with subdued geomagnetic conditions (RTSW 7-day).
Geomagnetism: Max Kp = 3+ (unsettled) on 25 Aug; G1 not reached. Min Dst ≈ −9 nT at 06:00 UTC, 26 Aug(quiet). Auroras confined to high latitudes.
Active regions & sunspots: AR 4199 was the standout and grew into the weekend. The International Sunspot Number stayed high (SILSO), with daily values around 190 ± 30.
Radio flux F10.7 (DRAO Penticton): Weekly mean ≈ 222 sfu (24–30 Aug), with a high daily value on 30 Aug(adjusted ~322.5 sfu at 20 UTC), typical after an LDE.
What’s next: SWPC keeps a G2–G3 watch for 01–02 Sep 2025 due to the 30 Aug CME; brief R1–R2 radio blackouts and moderate–strong geomagnetic intervals are possible depending on the CME’s evolution (see the 3-Day Forecast).
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