Over the course of June 19 to 20, 2025, the United States experienced short-lived disruptions in radio and GPS systems following a surge of solar activity, marked by two significant X-class solar flares detected by NASA’s Solar Dynamics Observatory (SDO). The more intense of the two, recorded on June 19, reached a strength of X1.9, making it one of the strongest solar flares observed so far this year.
These solar flares are part of a broader uptick in solar activity tied to Solar Cycle 25, which is expected to peak between late 2024 and 2026. Though X-class flares are the most powerful category and can trigger geomagnetic storms and communication disturbances, the flares recorded last week did not pose a threat to human health. Instead, their effects were felt primarily in the upper atmosphere, where they ionized the ionosphere and temporarily disrupted high-frequency (HF) communications and GPS signals.
The National Oceanic and Atmospheric Administration (NOAA) and the Federal Aviation Administration (FAA) both reported minor, temporary disruptions to radio transmissions and satellite-based navigation. These disruptions were primarily concentrated in polar and transoceanic flight routes, where high-frequency radio remains a critical communication method.
Maritime operations, which rely heavily on GPS for positioning and routing, also saw short-term signal irregularities. According to the U.S. Coast Guard Navigation Center, mariners were advised to expect degraded accuracy and potential delays in GPS-dependent services. Despite this, there were no major system failures or safety incidents reported.
Commercial airlines were notified in advance through Notices to Air Missions (NOTAMs), which helped mitigate operational impacts. Most air traffic continued without delays, thanks in part to backup communication and navigation protocols.Solar flares occur when magnetic energy built up in the Sun’s atmosphere is suddenly released, emitting a broad spectrum of electromagnetic radiation. The X-class categorization represents the most energetic flares, with an X1.0 flare being ten times more intense than an M1.0 flare.
These flares emit radiation that reaches Earth in about eight minutes, impacting the ionosphere and potentially disrupting technologies that depend on radio signals and satellite-based positioning. The intensity of the X1.9 flare on June 19 was enough to trigger a short-lived R3-level radio blackout on NOAA’s five-point space weather scale.
NASA also noted that these recent flares were not associated with coronal mass ejections (CMEs)—massive bursts of solar plasma and magnetic fields—which have the potential to cause far more severe and lasting geomagnetic storms. The absence of CMEs likely spared Earth from more significant impacts.
This latest event follows another X-class flare detected on June 17, reinforcing concerns among scientists that the Sun is entering a particularly active phase. The June 17 flare, classified as X1.2, was also captured by NASA’s Solar Dynamics Observatory and triggered similar but minimal communication issues.
Experts from NOAA’s Space Weather Prediction Center (SWPC) caution that if future solar flares coincide with CMEs, Earth could face more severe consequences. These might include prolonged satellite communication outages, disruptions to electrical grids, and elevated radiation exposure risks for astronauts and high-altitude pilots.
Dr. Rob Steenburgh, a space scientist at SWPC, noted in a statement that while current infrastructure is well-equipped to handle routine space weather, stronger events—comparable to the 1989 Quebec blackout or the historic Carrington Event of 1859—could test the resilience of modern technology.
In response to the increased solar activity, federal agencies have stepped up monitoring. NASA’s SDO, alongside NOAA’s GOES satellite series and other international instruments, are providing continuous real-time observations of solar behavior. These data streams are critical for forecasting solar events and issuing timely alerts to affected industries.
The FAA, U.S. Navy, and commercial satellite operators are part of a growing coalition that relies on these forecasts to maintain communication and navigation capabilities during space weather events. Additionally, scientific missions like the European Space Agency’s Vigil satellite and NASA’s Parker Solar Probe are contributing valuable insights into the mechanics of solar storms.
