On 18 March 2026, the British Geological Survey forecast prolonged geomagnetic storm conditions over the next 72 hours, driven by several coronal mass ejections expected to arrive between 19 and 21 March.[1][2] The first Earth-directed CME came from an M-class solar flare at 12:15 UT on 16 March from active region AR4392, with additional CMEs from filament eruptions and another M-class flare on 17 March, plus a further M-class flare and CME on the morning of 18 March.[1]
The forecast explicitly warned of prolonged STORM periods, with the strongest enhancement expected late on 19 March and elevated conditions persisting through 20–21 March; the timing was also near the spring equinox, which increases geomagnetic susceptibility.[1][2] For lunar habitation, this matters because storm-driven space weather can increase radiation exposure risk, degrade communications, disturb power systems, and stress unshielded or lightly shielded electronics, especially if surface assets are exposed during multi-day events.
The Ark team should treat this as a template for solar-weather readiness: maintain continuous monitoring of CME warning products, correlate storm alerts with power-load and communications resilience tests, and harden procedures for safe-mode transitions before arrival windows.[1][2] Priority should go to shielding audits, fault-tolerant timing/navigation systems, and store-and-forward communications that can survive multi-day outages or elevated noise during repeated CME impacts.