Date: 2026 May 25 0030 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
Solar activity remained at low levels. The majority of the C-class activity originated from Region 4446 (S13E59, Dko/beta) as it rotated further into view. The strongest flare was a C4.7 flare that peaked at 23/2359 UTC, with activity steadily declining throughout the rest of the period. There was a stray Type II radio sweep (est. 579 km/s) at 24/0850 UTC that was likely from a far-sided event. The CME signatures identified in available coronagraph imagery were associated with activity on or behind the Suns limb. No Earth-directed CMEs were observed in available satellite imagery.Newly numbered Region 4447 (S17E23, Dao/beta) was a separation of the northern spots from Region 4444 (S21E29, Hsx/alpha). Little change was observed in the other numbered regions.
Forecast: Solar activity is expected to remain at low levels, with a chance for isolated M-class flares (R1-R2/Minor-Moderate) on 25-27 May, primarily due to the flare potential of Region 4441 and Region 4446.Energetic Particle The greater than 2 MeV electron flux at geosynchronous orbit remained at moderate to high levels, reaching a peak level of 5,512 pfu at 24/1845 UTC. The greater than 10 MeV proton flux at geosynchronous orbit remained at background levels.
Forecast: The greater than 2 MeV electron flux is expected to remain at moderate to high levels on 25-27 May. The greater than 10 MeV proton flux is expected to remain at background levels through 27 May.
Solar wind parameters were indicative of near-background conditions. Wind speeds ranged from 270-356 km/s. Total magnetic field strength varied from 1-6 nT, Bz ranged between +/-5 nT, and the phi angle was predominantly in a negative orientation. The only enhancement in the solar wind parameters was an increase in density, rising from around 1 ppcm/3 to around 12 ppcm/3.
Forecast: Primarily ambient conditions are expected for 25 May under a continued background solar wind regime. Late on 26 May and into 27 May, enhancements to the solar wind environment are possible with the anticipated onset of a negative polarity CH HSS.
Forecast: Mostly quiet levels are anticipated on 25 May as a near-background solar regime persists. Periods of unsettled conditions are possible, with a chance for an isolated active periods, late on 26 May lasting into 27 May, with the likely onset of an approaching -CH HSS.