C5.2 solar flare erupts on June 18, 2025

A minor C5.2 solar flare erupted at 12:34 UTC on June 18, 2025.

Today’s flares include several C-class events, notably a C3.7 flare from region 4117 at 02:05 UTC, a C9.2 flare from region 4115 at 03:13 UTC, a C4.1 flare from region 4117 at 05:12 UTC, a C4.7 flare also from region 4117 at 05:33 UTC, two C5.5 flares (unattributed to a specific region) at 06:14 UTC and 06:25 UTC, and a C3.9 flare from region 4117 at 08:36 UTC. No M-class or X-class flares are recorded in the event data for June 18, 2025 as of 12:47 UTC.

In 24 hours to 12:30 UTC on June 18, solar activity reached high levels with an X1.2 flare observed at 21:49 UTC on June 17. Several additional moderate and minor flares were reported from various active regions.

There is a continued chance for R1 – Minor to R2 – Moderate radio blackouts, with a possibility of R3 – Strong X-class flares, primarily from active regions 4114, 4115, and 4117 through June 20, 2025.

There are currently 7 numbered active regions on the Earth-side of the Sun: AR 4109 (S17W0*, magnetic class Beta), AR 4110 (N05W98, Beta), AR 4111 (N15W37, Beta), AR 4113 (N10W22, Alpha), AR 4114 (N18W12, Beta-Gamma-Delta), AR 4115 (N20W01, Beta), and AR 4116 (S12W16, Beta).

Over the past 24 hours, greater than 2 MeV electron flux reached the 1000 pfu threshold due to influence from a high speed stream, while proton flux remained at background levels. Elevated electron flux levels are expected to persist, with a high chance for an S1 – Minor solar radiation storm on June 18, 2025 due to a recent CME.

Solar wind parameters during the past day indicated a positive polarity coronal hole high speed stream, with total magnetic field around 7–9 nT, Bz varying between +6 and -6 nT, and solar wind speeds averaging 450–510 km/s. A slight enhancement is possible on June 18 following an earlier CME, with similar conditions expected to persist through June 19, 2025.

Geomagnetic field conditions were quiet to unsettled. Quiet to active geomagnetic activity is forecast to continue into June 19 due to ongoing coronal hole stream effects. A G1 – Minor geomagnetic storm is likely on June 20, 2025, driven by a glancing impact from a CME.