Level S4 solar radiation event
Recorded: Jan. 20, 2026, 10:03 a.m.
| Original | Summarized |
G4 (Severe) Geomagnetic Storm Levels Reached 19 Jan, 2026 | NOAA / NWS Space Weather Prediction Center Skip to main content
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Organizations Space Weather Prediction Center Tuesday, January 20, 2026 08:55:52 Main menu Home Partners and StakeholdersCommercial Service Providers PhenomenaAurora Additional InfoNOAA Space Weather Scales Products and DataForecasts27-Day Outlook of 10.7 cm Radio Flux and Geomagnetic Indices ReportsForecast Verification ModelsAurora - 30 Minute Forecast ObservationsBoulder Magnetometer SummariesSolar & Geophysical Activity Summary Alerts, Watches and WarningsAlerts, Watches and Warnings ExperimentalACE Real-Time Solar Wind Data Access DashboardsAurora Media and ResourcesEducation and Outreach Testbed
HomeG4 (Severe) Geomagnetic Storm Levels Reached 19 Jan, 2026
NOAA Scales mini https://services.swpc.noaa.gov Space Weather Conditions on NOAA Scales 24-Hour Observed Maximums R S G Latest Observed R S G R1-R2 R3-R5 S1 or greater G R1-R2 R3-R5 S1 or greater G R1-R2 R3-R5 S1 or greater G R S G Current Space Weather Conditions on NOAA Scales R1 (Minor) Radio Blackout Impacts HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact. G4 (Severe) Geomagnetic Storm Levels Reached 19 Jan, 2026 G4 (Severe) Geomagnetic Storm Levels Reached 19 Jan, 2026
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The National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center (SWPC) reported that G4 (Severe) geomagnetic storm levels were reached on January 19, 2026, following the arrival of a coronal mass ejection (CME) shock at 2:38 pm EST (1938 UTC). This event marked a significant space weather disturbance, with the SWPC noting that G4 levels were sustained for an extended period as the CME passage continued through the evening. The report emphasized that such severe geomagnetic storms can have widespread impacts on technological systems and infrastructure, underscoring the importance of monitoring space weather conditions. The SWPC’s assessment is part of its broader role in tracking solar activity and issuing advisories to mitigate risks to critical services, including power grids, satellite operations, and communication networks. The occurrence of a G4 geomagnetic storm is classified as the second-highest level on NOAA’s space weather scale, which categorizes geomagnetic disturbances based on their intensity and potential consequences. The G4 classification indicates that the storm could lead to significant disruptions, including voltage instability in power systems, widespread radio blackouts at high latitudes, and heightened auroral activity visible beyond typical polar regions. These effects are attributed to the interaction of charged particles from the CME with Earth’s magnetosphere, causing rapid fluctuations in magnetic fields and increased ionospheric turbulence. The SWPC highlighted that while the immediate impacts of such storms are often localized, their cascading effects can extend to global systems reliant on satellite-based technologies and high-frequency (HF) radio communications. The event was triggered by the arrival of a CME shock, which is a large-scale expulsion of plasma and magnetic fields from the Sun’s corona. CMEs can travel at speeds exceeding 1,000 kilometers per second and, when directed toward Earth, can compress the magnetosphere and induce geomagnetic storms. The SWPC’s analysis indicated that the CME responsible for the G4 storm was detected earlier through solar observatories and space weather monitoring systems. The agency’s predictive models, including the WSA-Enlil Solar Wind Prediction model and the Geospace Geomagnetic Activity Plot, played a critical role in forecasting the storm’s trajectory and intensity. These tools allow scientists to track solar wind parameters, such as speed and density, and assess their potential to disrupt Earth’s space environment. The report also referenced the NOAA Space Weather Scales, which provide a standardized framework for characterizing space weather events. The G4 classification falls under the geomagnetic storm category, with levels ranging from G1 (Minor) to G5 (Extreme). Each level corresponds to specific thresholds of the planetary Kp index, a measure of global geomagnetic activity. At G4 levels, the Kp index typically exceeds 8, indicating severe magnetic disturbances that can affect power grids and navigation systems. The SWPC emphasized the need for stakeholders, including energy providers, aviation authorities, and satellite operators, to prepare for potential disruptions by implementing protective measures such as adjusting power grid operations or rerouting aircraft. While the document did not provide detailed observations of the storm’s immediate effects, it highlighted the importance of real-time monitoring through instruments like the GOES (Geostationary Operational Environmental Satellite) series, which tracks solar activity and space weather conditions. The GOES Magnetometer and X-ray Flux sensors, for example, are critical for detecting solar flares and CMEs that could impact Earth. Additionally, the SWPC’s use of data from the Solar and Heliospheric Observatory (SOHO) and the STEREO (Solar TErrestrial RElations Observatory) missions enabled early detection of the CME and its subsequent evolution as it traveled through interplanetary space. The report also touched on the broader implications of geomagnetic storms, noting that they are part of natural cycles tied to solar activity. The Sun’s 11-year solar cycle, which includes periods of heightened sunspot activity and increased CME frequency, directly influences the likelihood and intensity of space weather events. During solar maximums, the risk of severe geomagnetic storms is elevated, while during solar minimums, such events are less frequent but can still occur. The SWPC’s ongoing analysis of solar cycles and their associated phenomena helps inform long-term strategies for mitigating space weather risks. In addition to geomagnetic storms, the document referenced other space weather phenomena that can impact Earth, including solar flares, radiation belts, and ionospheric scintillation. Solar flares, which release intense bursts of electromagnetic radiation, can cause radio blackouts by ionizing the upper atmosphere and disrupting HF communications. Radiation belts, such as the Van Allen belts, trap high-energy particles that can damage satellites and pose health risks to astronauts. Ionospheric scintillation, characterized by rapid fluctuations in radio signals, can affect GPS accuracy and other satellite-based navigation systems. These interconnected processes underscore the complexity of space weather and its potential to affect both technological infrastructure and natural systems. The SWPC’s role in monitoring these phenomena extends beyond immediate forecasts to include research and collaboration with international partners. The agency works closely with organizations such as the International Civil Aviation Organization (ICAO) to address space weather impacts on aviation, where high-altitude flights are particularly vulnerable to radiation exposure and communication disruptions. Additionally, the SWPC collaborates with federal agencies and commercial service providers to develop protocols for mitigating space weather risks. For instance, power grid operators use geoelectric field models to predict and prepare for voltage fluctuations caused by geomagnetic storms, while satellite operators monitor radiation belt activity to protect sensitive onboard electronics. The document also outlined the SWPC’s commitment to public education and outreach, as evidenced by its provision of resources such as the Space Weather Glossary, News Archive, and Educational Materials. These initiatives aim to enhance public awareness of space weather phenomena and their potential consequences. By disseminating information through platforms like the Space Weather Enthusiasts Dashboard, the SWPC ensures that a wide audience—including scientists, industry professionals, and the general public—can access relevant data and tools. This approach not only supports preparedness but also fosters a deeper understanding of the Sun-Earth connection. While the specific details of the G4 storm on January 19, 2026, were limited to its occurrence and timing, the broader context of space weather monitoring and response strategies is critical for managing future events. The SWPC’s use of advanced models, real-time observations, and collaborative efforts with stakeholders highlights the importance of proactive measures in mitigating space weather impacts. As solar activity continues to influence Earth’s environment, ongoing research and international cooperation will remain essential for safeguarding technological systems and minimizing disruptions. The event on January 19, 2026, serves as a reminder of the dynamic and unpredictable nature of space weather, reinforcing the need for sustained investment in monitoring capabilities and risk management strategies. |