Minor C7.1 solar flare erupts at 11:19 UTC on September 4, 2026

A minor C7.1 solar flare erupted at 11:19 UTC on September 4, 2026.

Today’s flares include a C1.5 flare at 02:44 UTC, a C1.3 flare at 06:15 UTC, and an M1.2 flare that peaked at 07:53 UTC from active region 4524.

In 24 hours to 03:05 UTC on September 4, solar activity was at low levels with regions producing multiple C-class events. The strongest flare prior to the C7.1 event was a C7.0 at 14:46 UTC and a C7.9 at 16:30 UTC on September 3. Associated CMEs during this period are not expected to be Earth-directed.

Solar activity will likely remain at low levels with occasional C-class events and a slight chance for moderate M-class flares (R1-R2 – Minor to Moderate) through September 6.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4521 (N09E26 – Alpha), AR 4523 (N10E36 – Beta), and AR 4524 (N12E66 – Alpha).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels with a peak flux of 2 700 pfu, while the greater than 10 MeV proton flux remained at background levels. The electron flux is expected to stay at high levels through September 4, then decrease to normal-to-moderate levels by September 5–6, while proton flux will continue at background values.

Solar wind parameters remained mostly nominal with a slightly elevated total field of 8 nT, and a benign Bz component fluctuating between -4 and 6 nT. Wind speeds stayed largely below 400 km/s. Ambient-like solar wind conditions are expected through September 5, with possible enhancements by late September 6 due to a solar sector boundary crossing.

The geomagnetic field was quiet in the previous 24 hours and is forecast to remain mostly quiet through September 5. Isolated unsettled conditions are likely by late September 6 related to solar sector boundary effects.