Minor C8.1 solar flare erupts at 18:49 UTC on April 28, 2026

A minor C8.1 solar flare erupted at 18:49 UTC on April 28, 2026.

The C8.1 flare began at 18:43 UTC, reached its peak at 18:49 UTC, and ended at 18:53 UTC from active region 4425. Today’s flares include several C-class and low M-class events, with the largest being an M1.5 flare at 13:53 UTC and three moderate M-class events (M1.0 at 12:23 UTC, M1.5 at 13:53 UTC, M1.1 at 14:07 UTC), all originating from region 4420 and 4425.

In 24 hours to 12:30 UTC on April 28, solar activity remained at low levels, with the majority of C-class flares produced by regions 4420 and 4425. No Earth-directed coronal mass ejections were observed in available imagery.

Solar activity is expected to be at low levels, with a high likelihood to reach moderate levels (R1/R2 – Minor/Moderate), and a chance for X-class (R3 – Strong or greater) events through April 30, due primarily 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, the greater than 2 MeV electron flux at geosynchronous orbit was at low to moderate levels. The greater than 10 MeV proton flux remained at background levels. The greater than 2 MeV electron flux is anticipated to reach moderate to high levels on April 30 due to coronal hole high-speed stream influence. There is a slight chance the greater than 10 MeV proton flux could reach S1 – Minor levels on April 28-30 due to the flare potential of regions 4420 and 4425.

Solar wind parameters were near nominal levels over the past 24 hours, with solar wind speeds decreasing from around 450 to 360 km/s. The total field ranged from 2–6 nT, and the Bz component was between +5/-3 nT. The phi angle was mostly positive. Solar wind parameters are expected to remain at or near nominal levels through midday on April 29, with an increase expected by mid to late on April 29 due to the onset of a negative polarity coronal hole high-speed stream. These conditions are likely to persist through April 30, with solar wind speeds in the 450–550 km/s range.

The geomagnetic field was at quiet levels over the past 24 hours. Mostly quiet geomagnetic conditions are expected on April 28, with an increase to unsettled to active levels expected for April 29-30 due to the onset of a negative polarity coronal hole high-speed stream.