C9.9 solar flare erupts on June 17, 2025

A moderate C9.9 solar flare erupted at 06:21 UTC on June 17, 2025.

Today’s flares include a C4.1 event from region 4113 peaking at 00:53 UTC, a C6.8 event from region 4114 peaking at 01:26 UTC, along with several C-class radio sweep events reported at various times.

In 24 hours to 00:30 UTC on June 17, solar activity was at high levels with several R1 – Minor to R2 – Moderate level flares observed, notably an M6.3 and M1.8 from region 4114, and an M1.4 from region 4109. C-class activity was also recorded from multiple regions.

There is a 75% chance flaring will reach moderate levels (R1 – Minor to R2 – Moderate) with a 30% chance for X-class flares (R3 – Strong) on June 17-19, mainly due to region 4114’s increasing size and magnetic complexity.

There are currently 7 numbered active regions on the Earth-side of the Sun: AR 4105 (S14W98 – Beta), AR 4109 (S17W90 – Beta), AR 4110 (N05W83 – Beta), AR 4111 (N15W26 – Beta), AR 4113 (N10W09 – Alpha), AR 4114 (N18W01 – Beta-Gamma-Delta), and AR 4116 (S11W03 – Beta).

Over the past 24 hours, the greater than 2 MeV electron flux was at normal to moderate levels and the greater than 10 MeV proton flux remained at background. The electron flux is expected to be at moderate to high levels on June 17-19 under continued coronal hole high speed stream influence. Protons are expected to remain at background levels through June 19.

Solar wind parameters over the past 24 hours reflected persistent coronal hole high speed stream conditions, with the total field around 8 nT, fluctuating north-south component between +/-9 nT, and speeds in the 470-520 km/s range. These conditions are forecast to persist through June 19, with a slight chance of enhancement on June 18 from an expected interplanetary shock.

The geomagnetic field was at quiet to active levels during the past 24 hours. Coronal hole high speed stream activity is expected to continue causing unsettled to active periods through June 19, with a slight chance for an isolated period of G1 – Minor geomagnetic storming from the possible arrival of an interplanetary shock.