Minor C9.0 solar flare erupts at 09:23 UTC on April 28, 2026

A minor C9.0 solar flare erupted at 09:23 UTC on April 28, 2026.

Today’s flares include a C2.3 event from region 4420 (max at 01:03 UTC) and a C2.7 event from region 4425 (max at 01:32 UTC).

In 24 hours to 00:30 UTC on April 28, solar activity was at moderate levels, due to an M1.0 flare observed at 06:45 UTC on April 27. The majority of C-class flares were produced by active regions 4420 and 4425. Slight decay was noted in region 4420, moderate growth in region 4425, and slight growth in region 4424. An M6.0 flare at 22:57 UTC on April 26 showed ejecta in SUVI 304 imagery, but model analysis indicated no Earth-directed CME component.

Solar activity is expected to remain at low levels, with a high likelihood to reach moderate levels and a chance for X-class events through April 30, primarily due to the complexity of regions 4420 and 4425.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4420 (N16W29 – Beta-Gamma-Delta), AR 4421 (S12W17 – Alpha), AR 4423 (S05W10 – Beta), AR 4424 (N16E06 – Beta), AR 4425 (N05E36 – Beta-Gamma-Delta), and AR 4427 (S31E40 – Alpha).

Over the past 24 hours, greater than 2 MeV electron flux at geosynchronous orbit was at low to moderate levels, and greater than 10 MeV proton flux remained at background levels. The greater than 2 MeV electron flux is expected to reach moderate to high levels on April 30, with a slight chance for S1 – Minor solar radiation storm levels between April 28 and 30.

Solar wind conditions were near nominal, with speed ranging from 405 to 488 km/s, total field at 2–6 nT, and Bz between +5 and -3 nT. Parameters should remain near nominal through midday April 29, increasing by mid to late April 29 as a negative polarity coronal hole high speed stream arrives. Elevated conditions are likely through April 30, with solar wind speeds anticipated in the 450–550 km/s range.

The geomagnetic field ranged from quiet to unsettled levels in the past 24 hours. Mostly quiet conditions are expected on April 28, with an increase to unsettled and active levels anticipated on April 29–30 as the high speed stream influence develops.