Forecast for G2 Geomagnetic Storm Following X1.9 Solar Flare on December 1, 2025

The opening days of December 2025 brought renewed focus to space weather events following a significant solar eruption. This incident, triggered by an intense solar flare and a subsequent Coronal Mass Ejection (CME), began with the registration of an X1.9-class flare on Monday, December 1, 2025. The flare reached its peak intensity at 02:49 Greenwich Mean Time. This powerful outburst originated from the active region designated AR4299 and had already caused severe R3-level radio blackouts across Australia and parts of Southeast Asia by December 2.

The U.S. National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (NOAA SWPC), in collaboration with NASA, has issued an official advisory. Their forecast anticipates the potential for a G2-level geomagnetic storm—classified as Moderate—to occur on Wednesday, December 3, and Thursday, December 4, 2025. Experts suggest that the CME might only deliver a glancing blow to Earth's magnetosphere. However, this impact could be amplified. An additional concern arises from the potential coincidence with an incoming high-speed stream originating from a coronal hole (CH HSS), which could temporarily elevate the storm intensity to G3, or Strong level.

The interaction between the CME and the Earth's magnetic field is the crucial factor for technological infrastructure. Coronal Mass Ejections, which are essentially clouds of magnetized plasma, can travel toward Earth at speeds ranging from a mere 100 kilometers per second to over 3,000 kilometers per second. Such events possess the capability to compress the magnetopause to a point inside the orbits of geosynchronous satellites, thereby stripping them of their protective shielding and exposing sensitive electronics to danger. For this specific event, the threat profile includes potential temporary disruptions to satellite systems, reduced accuracy in GPS signals, and interruptions to mobile and radio communications.

Should the storm reach G2 intensity, the resulting moderate field fluctuations could trigger the appearance of auroras far south of their usual latitudes and induce voltage surges capable of damaging power transformers. The coordinated international response to this space weather threat highlights effective collaboration among global agencies. Beyond the NOAA SWPC, specialists from NASA and the Russian Academy of Sciences' Solar Physics Laboratory, particularly researchers from the Space Research Institute (IKI RAN), are actively engaged in the analysis.

This period of heightened activity is part of a broader pattern. The same region, AR4299, previously known as AR4274, was responsible for a significant X5.1 flare on November 11, 2025, along with other strong eruptions during November. While December is typically a quieter month, the solar activity observed in 2025, according to NOAA data, is deviating from the expected norms. The unique aspect of the current situation lies in the possibility of a synergistic effect: the CH HSS might accelerate the CME's plasma cloud, which is what underpins the probability of reaching G3 status.

Alongside the technological hazards, there is an anticipated aesthetic consequence: the geomagnetic disturbances might make the aurora borealis visible even in the northern states of the U.S. The inherent uncertainty in precisely gauging the impact strength necessitates heightened vigilance, as recommended by NOAA guidelines. Monitoring efforts are ongoing to accurately determine the extent to which Earth’s geomagnetic field will be disturbed over the next forty-eight hours.