Space Weather Scale for Geomagnetic Storms
Physical measure* | (1 cycle=11 years) |
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G1 | ![]() |
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Kp=5 | 1700 per cycle (900 days per cycle) |
G2 | ![]() |
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Kp=6 | 600 per cycle (360 days per cycle) |
G3 | ![]() |
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Kp=7 | 200 per cycle (130 days per cycle) |
G4 | ![]() |
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Kp=8 | 100 per cycle (60 days per cycle) |
G5 | ![]() |
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Kp=9 | 4 per cycle (4 days per cycle) |
* The K-index used to generate these messages are derived in real-time from the Boulder Magnetometer. The Boulder K-index, in most cases, approximates the Planetary Kp-index referenced in Space Weather Scales. The Planetary Kp-index is not available in real-time.
** For specific locations around the globe, use geomagnetic latitude to determine likely sightings (Tips on Viewing the Aurora)