S1 – Minor Solar Radiation Storm Alert issued on May 26, 2026

An S1 – Minor Solar Radiation Storm Alert was issued by the NOAA Space Weather Prediction Center on May 26, 2026. The alert was triggered at 00:10 UTC after the 10 MeV integral proton flux exceeded the threshold of 10 pfu, corresponding to the S1 – Minor level on the NOAA Space Weather Scale. The alert was officially issued at 00:35 UTC.

An S1 – Minor Solar Radiation Storm typically indicates minor impacts on space-based technological systems. This level of event may cause minor impacts to high-latitude HF radio operations and present a low risk of radiation exposure for passengers and crew in high-flying aircraft at high latitudes. No significant impacts are expected for the general public or for most technological systems at the Earth’s surface.

The alert follows a period of elevated energetic particle activity, attributed to far-side solar activity. The greater than 10 MeV proton flux became elevated late in the period but remained below major threshold values prior to this event, according to the SWPC forecast discussion issued May 26, 2026. No Earth-directed coronal mass ejections were observed during this period, and solar activity otherwise remained at low levels with only occasional C-class flaring.