Minor C9.7 solar flare erupts at 20:53 UTC on May 17, 2026

A minor C9.7 solar flare erupted at 20:53 UTC on May 17, 2026.

Today’s flares include a moderate M1.4 flare at 03:39 UTC from region 4435, numerous C-class flares (C1.0 at 04:44 UTC, C2.0 at 05:32 UTC, C1.1 at 11:32 UTC from region 4436, C1.0 at 12:07 UTC from region 4439, and C1.1 at 12:38 UTC from region 4438), along with several B-class events.

In 24 hours to 12:30 UTC on May 17, solar activity was at moderate levels, highlighted by an M1.9 flare at 16:12 UTC and an M1.3 flare at 16:29 UTC, both followed by a complex CME and radio emission, primarily passing north of Earth by May 18.

Solar activity is likely to be at low levels, with a chance for additional M-class (R1 – Minor to R2 – Moderate) flares through May 19, 2026.

Over the past 24 hours, the greater than 2 MeV electron flux increased to high levels, while greater than 10 MeV proton flux remained at background levels. The electron flux is expected to remain at moderate to high levels through May 19, with proton flux staying at background levels through May 18.

Solar wind parameters reflected continued influence of a negative polarity coronal hole, with total magnetic field strength steady near 5 nT, Bz ranging between +/- 5 nT, and wind speeds in the 600-700 km/s range. The phi angle was predominantly in a negative solar sector. This regime is expected to persist through May 19, with possible enhancements on May 18 and 19 due to a glancing CME.

The geomagnetic field reached G1 – Minor geomagnetic storm levels during the reporting period due to effects from a negative polarity coronal hole high speed stream. G1 – Minor geomagnetic storming is likely on May 17 due to continued high speed stream effects, with a chance for G2 – Moderate levels on May 18 due to any glancing CME influences. There is a continued chance for G1 – Minor storming through May 19.