The Kp index is a global measure of geomagnetic disturbance, produced every three hours by combining data from a network of ground magnetometer observatories spread across the world. Each station measures how far its local magnetic field has wandered from a quiet baseline, converts that into a local, quasi- logarithmic K-index (0–9), and the planetary average of those local K-values — weighted for each station's magnetic latitude — becomes Kp.
NOAA's G-scale reuses the Kp value directly: Kp 5 is G1 (Minor), rising to Kp 9, which is G5 (Extreme) — the level reached during the May 2024 storm, the strongest in over two decades, which pushed visible aurora as far south as Mexico and southern Europe.
A 3D globe ringed by twelve stand-in magnetometer observatories and a glowing auroral oval that expands toward the equator as the planetary Kp index climbs from quiet to extreme storm levels.
Kp is derived by averaging local K-index disturbance readings from stations scattered across magnetic latitudes worldwide; as Kp rises, disturbance spreads from polar stations down toward the equator, and the auroral oval's edge follows the same equatorward push.
Drag the Kp slider from 0 to 9 and watch which observatories light up and how far the oval creeps down. Set an observer latitude to check whether the aurora would be visible from that location, or let "Simulate rising storm" animate a full storm cycle.
NOAA's Space Weather Prediction Center reuses Kp directly as its G-scale: G1 (Minor) starts at Kp 5, and G5 (Extreme) at Kp 9 — the level reached during the May 2024 storm that carried aurora as far south as Mexico and southern Europe.