Geomagnetic Storm 2025 Map. May 2025 geomagnetic storm was one of the strongest since 2002. The most recent g4 (severe) storm occurred on march 23, 2025, while the halloween storms in october 2003 marked the last g5 (extreme) event.
Sharply negative values are associated with. Weak or minor degradation of hf radio communication on sunlit side, occasional loss of radio contact.